Tests for a bounded, streamed --repeat, rune-named flags, and --list with inert flags

.github/workflows/test.yml

@@ -16,28 +16,12 @@ jobs:
       - uses: actions/checkout@v6
         with:
           persist-credentials: false
-          fetch-depth: 0
-      - name: Relevant changes
-        id: changes
-        run: |
-          if [ "$GITHUB_EVENT_NAME" = "pull_request" ]; then
-            git fetch --no-tags origin "$GITHUB_BASE_REF"
-            base="origin/$GITHUB_BASE_REF"
-          else
-            base='${{ github.event.before }}'
-          fi
-          if git diff --quiet "$base"...HEAD -- '*.go' go.mod go.sum Dockerfile .dockerignore .github data README.md; then
-            echo "code=false" >> "$GITHUB_OUTPUT"
-          else
-            echo "code=true" >> "$GITHUB_OUTPUT"
-          fi
       # `docker build` streams the context to the daemon. A compose bind-mount of
       # `.` mounts an empty host dir instead, because the job is itself a container.
       - name: Latest supported Go
-        if: ${{ steps.changes.outputs.code == 'true' }}
         run: docker build .
       # Runs even when the step above failed, so a red build says whether the
       # failure is version-specific.
       - name: Lowest supported Go
-        if: ${{ !cancelled() && steps.changes.outputs.code == 'true' }}
+        if: ${{ !cancelled() }}
         run: docker build --build-arg GO_VERSION=1.22.12 .

.gitignore

@@ -1,3 +1,4 @@
 .claude
 *.out
 __pycache__/
+todo.md

AGENTS.md

@@ -8,3 +8,11 @@
 - A standing choice a reader would relitigate goes under Decisions in the README, not in a comment.
 - A README example is a `json` block that loads and renders as a category; `readme_test.go` runs every one.
 - Cyclomatic complexity is gated at 14: the table-shaped dispatches (`eachToken`, `calc.factor`, `walkPath`) sit at 13–14 and stay whole; anything else that reaches 14 is decomposed.
+
+# Deferred
+
+- **Shipped-data de-duplication (2026-09-02).** `email.json`'s `local` is a
+  drifted copy of `username.json`, and no shipped file yet uses a held path, an
+  operand or a reference. Fixed in the data fill before the first tag, when the
+  shipped set is rewritten anyway; premise: nothing depends on the shipped data's
+  shape until then. Not raised in review before that.

README.md

@@ -1,17 +1,32 @@
 # fejkdata
 
-Locale-aware fake data for tests and fixtures, generated from JSON templates. Use
-it as a Go library or the CLI — no data on disk, no dependencies, and a seed makes output
-reproducible.
+A Go library and CLI for generating locale-aware fake data from JSON templates.
+Forked from [github.com/Timewave-AB/fakes](https://github.com/Timewave-AB/fakes).
 
-```sh
-go install gitea.larvit.se/larvit/fejkdata/cmd/fejkdata@latest
-fejkdata sv_SE.person          # Sara Eriksson
-```
+## Goals
+
+1. **Valid by construction** — every value passes the check its real consumer
+   applies; facts that belong together come from one draw, within a value and
+   across categories.
+2. **Text means what it says** — a format renders as written; only `{…}` varies,
+   random characters included (`{digits(3)}`). One spelling per result; the wrong
+   one is a load error naming the right one.
+3. **Every mistake is a load error** — `New` rejects; `Fake` on a loaded generator
+   fails only for an unknown path.
+4. **Zero to a value in one command** — `go install`, then `fejkdata sv_SE.person`:
+   no checkout, no flag. Flags are GNU-form (`--seed 42`, `-n 3`) in any position;
+   the first custom template needs no escape and no option.
+5. **Data lives in JSON** — a builtin only for what data can't express.
+6. **Reproducible** — seed in, same stream out; no builtin reads a clock.
+7. **Zero dependencies** — standard library only.
+8. **Docs index the grammar** — every syntax feature is a heading; every example
+   runs under test and shows its output; a rule is stated once.
 
 ## CLI
 
 ```sh
+go install gitea.larvit.se/larvit/fejkdata/cmd/fejkdata@latest
+
 fejkdata sv_SE.person                          # Sara Eriksson
 fejkdata sv_SE.person.last                     # Eriksson
 fejkdata --seed 42 sv_SE.address               # the same address every run
@@ -19,27 +34,17 @@ fejkdata -n 3 --separator ', ' sv_SE.word      # nät, barn, sol
 fejkdata --list                                # every path the data offers
 fejkdata --data-path ./mydata sv_SE.word       # layer a directory over the shipped data
 fejkdata --no-shipped-data -d ./mydata --list  # only your data
-fejkdata 'name: {/sv_SE.person.last}'          # name: <a surname> — an inline template
-fejkdata '{"format":"name: {x}","x":["bosse","lina"]}'  # name: bosse or name: lina
 ```
 
 A path names a category, or a field inside one: each dot segment descends one
-level — folders, then the category (a JSON file), then fields. An argument that is
-a JSON object, array or string, or that carries a `{` token, is instead an
-**inline template**: a format string or a JSON value compiled and rendered on the
-spot. Its tokens reach the data by reference from the root —
-`{/sv_SE.person.last}`, so shipped and `--data-path` categories are alike
-available. An inline template sits in no folder, so the folder-relative `{.name}`
-and `{..name}` are rejected naming the root spelling. A path never contains a
-brace, a bracket or a quote, so the two cannot collide (see
-[Decisions](#decisions)).
+level — folders, then the category (a JSON file), then fields.
 
 | Flag | |
 |------|--|
 | `-d`, `--data-path D` | a directory to layer over the shipped data; repeatable, the last wins a name clash |
 | `--no-shipped-data` | load only the `--data-path` directories |
 | `-s`, `--seed N` | reproducible output |
-| `-n`, `--repeat N` | render the value N times (up to 1048576), each an independent draw, streamed |
+| `-n`, `--repeat N` | render the path N times, each an independent draw |
 | `--separator S` | between repeated values (default a newline) |
 | `--list` | print every path, then exit |
 | `--version`, `-h`, `--help` | print, then exit |
@@ -47,9 +52,7 @@ brace, a bracket or a quote, so the two cannot collide (see
 `--name value` and `--name=value` both work, a short flag's value attaches or
 follows (`-n3`, `-n 3`) and short flags bundle (`-hn 3`) — see
 [Decisions](#decisions); flags go anywhere, `--` ends them. Exit codes: `0` success, `1` runtime error (missing
-dir, unknown path), `2` misuse — a bad flag, an argument that names neither a
-template nor a path, or an inline template that does not compile. From a checkout:
-`go run ./cmd/fejkdata …`.
+dir, unknown path), `2` misuse. From a checkout: `go run ./cmd/fejkdata …`.
 
 ### Your own data
 
@@ -86,9 +89,6 @@ if err != nil {
 }
 v, err := f.Fake("sv_SE.address") // "Kungsvägen 68\n379 17 Stockholm"
 paths := f.List()                  // every path Fake accepts, sorted
-v, err = f.FakeTemplate("name: {/sv_SE.person.last}")      // compile + render in one call
-t, err := f.NewTemplate(`{"format":"name: {x}","x":["bosse","lina"]}`) // compile once
-v = t.Fake()                                              // render many times, no re-parse
 ```
 
 | Option | |
@@ -110,8 +110,8 @@ work with no data on disk. A directory is a namespace: each JSON file is a
 category named after the file, each subdirectory a dot-path segment, so
 `mydata/sv_SE/person.json` is `sv_SE.person` and replaces the shipped one.
 Sources merge in order; matching folders combine, any other clash is won by the
-last loaded. Names may not use `.`, `|`, `(`, `{`, `}`, `[`, `]`, `"` or `/`;
-dot-prefixed entries are skipped, so a data directory can also be a checkout.
+last loaded. Names may not use `.`, `|`, `(`, `{`, `}` or `/`; dot-prefixed entries
+are skipped, so a data directory can also be a checkout.
 
 Each locale carries `address`, `color`, `company`, `date`, `email`, `ip`,
 `person`, `phone`, `price`, `sentence`, `ssn`, `time`, `url`, `username`,
@@ -180,9 +180,9 @@ many times — each an independent draw — joined by `separator` (default `""`)
 { "format": "{word}", "repeat": 3, "separator": " ", "word": ["foo", "bar", "baz"] }
 ```
 
-Renders e.g. `bar foo baz`. Rejected at load: a `separator` without a `repeat`,
-a `separator` of `""` (the default), and a `repeat` that multiplies to more than
-1 048 576 renders along any path of nested repeats.
+Renders e.g. `bar foo baz`. A `separator` without a `repeat` is rejected, and so
+is a `repeat` that multiplies to more than 1 048 576 renders along any path of
+nested repeats.
 
 ### Options and fields
 
@@ -194,11 +194,9 @@ choice naming its item.
 ### Functions
 
 A `{name(args)}` token calls a builtin. Arguments are checked at `New`: a bad
-count, range, country or expression fails fast; an integer is written plain
-(`5`, not `+5` or `05`); bounds are finite; a sample that could only ever emit one
-value (`int(5,5)`, `float(1,1,2)`) is rejected naming the text to write instead;
-and a length, count or decimal place beyond a sane maximum is rejected, so a
-fat-fingered `hex(2000000000)` never tries to allocate gigabytes. Every builtin draws only from the seed — a
+count, range, country or expression fails fast, and a length, count or decimal
+place beyond a sane maximum is rejected, so a fat-fingered `hex(2000000000)`
+never tries to allocate gigabytes. Every builtin draws only from the seed — a
 time-based id takes its timestamp from the rng, not the clock — so seeded output
 stays reproducible.
 
@@ -245,10 +243,8 @@ hyphenated field can't be an operand.
 ```
 
 Renders e.g. `19.99 x 3 = 59.97`. An operand that can never be a number (`"abc"`,
-or a choice of such) is rejected at load, as is a division by a constant zero
-(`1/0`, or a fixed `"0"` field); an operand that sometimes is not a number yields
-`NaN`, and a division by one that is not constant `Inf` — both print rather than
-fail.
+or a choice of such) is rejected at load; one that sometimes is not yields `NaN`,
+and a division by zero `Inf` — both print rather than fail.
 
 ### Transforms
 
@@ -341,29 +337,6 @@ then costs about what its output costs: an unweighted pick is O(1) whatever the
 list's length, a weighted one O(log n), and long formats, deep nesting and many
 tokens add cost in proportion to the output.
 
-## Goals
-
-1. **Valid by construction** — every value passes the check its real consumer
-   applies; facts that belong together come from one draw, within a value and
-   across categories.
-2. **Text means what it says** — a format renders as written; only `{…}` varies,
-   random characters included (`{digits(3)}`). One spelling per result; the wrong
-   one is a load error naming the right one.
-3. **Every mistake is a load error** — `New` rejects the data and `NewTemplate`
-   the inline template; on a loaded generator `Fake` fails only for an unknown
-   path, and `Template.Fake` cannot fail at all.
-4. **Zero to a value in one command** — `go install`, then `fejkdata sv_SE.person`:
-   no checkout, no flag. Flags are GNU-form (`--seed 42`, `-n 3`) in any position;
-   the first custom template needs no escape and no option.
-5. **Data lives in JSON** — a builtin only for what data can't express.
-6. **Reproducible** — seed in, same stream out; no builtin reads a clock.
-7. **Zero dependencies** — standard library only.
-8. **Docs index the grammar** — every syntax feature is a heading; every example
-   runs under test and shows its output; a rule is stated once.
-9. **Fast enough to be free** — a value renders in about a microsecond and `New`
-   parses and validates the whole set once upfront, so generating fixtures stays
-   noise against a test's own runtime.
-
 ## Decisions
 
 - **Options and fields share one namespace.** `format`, `weight`, `repeat` and
@@ -379,33 +352,6 @@ tokens add cost in proportion to the output.
   naming the double-dash spelling, and `-s=42` is rejected naming both short
   spellings: `=` belongs to the long form, and reading `=42` as the value would
   make `-d=./x` a directory named `=./x`.
-- **An argument is a template by its shape, not by a flag.** A JSON object, array
-  or string, or a string carrying a `{` token, is an inline template; anything else
-  is a path. A name may not contain a brace, a bracket or a quote, so a path can
-  never collide with any of those spellings, and the leading `[` or `"` is gated on
-  valid JSON so a stray copied bracket never swallows an argument — it names
-  nothing, and says so. No `--template` flag is needed. Reserving the characters
-  whole — though only a leading one could collide — keeps one simple name rule
-  instead of a leading-position special case. The JSON string is what makes the
-  library's own advice reachable: the error for an object holding only a format
-  names `"…"`, and that spelling has to work where it is printed.
-- **An inline template skips the cycle fence, and only that one.** `New` proves the
-  loaded tree acyclic, an inline node is a finite tree of its own, and nothing in
-  the tree can reference it, so no render of it reaches itself. Every other fence
-  runs over both, from one `checkScope`.
-- **An inline template that does not compile is misuse (exit 2), including a
-  reference that resolves to nothing** — the whole argument is the spelling under
-  test, and `NewTemplate` compiles, links and validates as one step. An unknown
-  *path* stays a runtime error (exit 1): there the argument is well-formed and only
-  the data is absent.
-- **A padded JSON argument is rejected, not trimmed.** Padding is the one place the
-  two readings disagree — a format string renders it, JSON drops it — so the
-  spelling that renders is named rather than silently chosen.
-- **`FakeTemplate` and `NewTemplate` both stay.** They reach the same value but not
-  at the same cost: `NewTemplate` pays the compile and validation once and renders
-  many times, `FakeTemplate` is the one-shot call, and `--repeat` is exactly the
-  case that needs the first. The pair is `regexp.MustCompile` and `regexp.Match`,
-  not two spellings of one result.
 - **The shipped data is embedded, not discovered.** A directory a machine happens
   to have would make `--seed 42` machine-dependent. Data still lives in `data/`
   as JSON; `--data-path` layers over it.
@@ -433,33 +379,9 @@ tokens add cost in proportion to the output.
   when that file lacks a field those references read. Accepted: overriding is the
   point of layering, the error names the reference and the field, and the fix is
   the consumer's file carrying the fields the shipped tree reads.
-- **The repeat cap bounds renders, not bytes.** A repeat, alone or nested, may
-  ask for at most 1 048 576 renders; how large each render is stays what the data
-  asked for, so `{hex(1048576)}` repeated to the cap is a terabyte, loaded without
-  complaint. A byte estimate would need every builtin to declare a width to fence
-  a shape no data comes near, and the harm lands on the author who wrote it.
-- **64-bit targets only.** The gate builds amd64, and the buffer sizing a render
-  pre-computes (renders × bytes) assumes a 64-bit int; on a 32-bit target it could
-  overflow and panic.
-- **A constant zero divisor is a load error; a divisor that is not constant prints
-  `Inf`.** `1/0` and a fixed `"0"` field are decidable, so they join the
-  never-numeric operand as a load error; the fold stops where an operand varies,
-  so `a/(b*c)` with `b` fixed at `0` and `c` varying loads and prints `Inf` every
-  draw — catching it needs zero-absorbing algebra for a shape nobody writes.
-- **In data, a default written out and a constant spelled as a sample are load
-  errors.** `weight: 1`, `repeat: 1`, `separator: ""`, `int(5,5)`, `float(1,1,2)`,
-  `+5` and `05` each spell what a shorter form already spells, so each is rejected
-  naming that form. The CLI's numbers follow the shell instead: `--seed 007` and
-  `--repeat +3` are 7 and 3, as every command line reads them.
 - **Samples say what they emit, transforms what they do.** `{upper(2)}` is two
   letters, `{uppercase(x)}` is `x` upper-cased; one name for both would turn on
   whether the argument looks like a number.
-- **The performance gate asserts allocations, not wall-clock time.** `AllocsPerRun`
-  is deterministic across machines, so a ±10% ceiling does not flake under CI load,
-  while time varies with the machine and its neighbours. A rendering slowdown
-  almost always costs an allocation too (a lost pre-size, a per-item map, an extra
-  copy). The benchmark suite (see Development) reports time for a human, not as a
-  pass/fail gate.
 
 ## Development
 
@@ -484,10 +406,8 @@ docker compose run --rm --user "$(id -u):$(id -g)" tidy  # go mod tidy
 ```
 
 Every pull request runs `docker build .` against both the latest and the lowest
-supported Go, and must pass before it can be merged — unless it changes none of
-the files the build and its tests read, nor the workflow itself, in which case
-it's skipped (see [Decisions](#decisions)). That build is the whole gate — vet,
-complexity, format check and tests — so run it locally before pushing:
+supported Go, and must pass before it can be merged. That build is the whole
+gate — vet, complexity, format check and tests — so run it locally before pushing:
 
 ```sh
 docker build .                                  # latest
@@ -502,7 +422,6 @@ fejkdata.go     Generator, New, options, the embedded data set, List
 node.go         the node model and JSON -> node compilation
 path.go         the dotted-path walk, and proving a path resolves
 render.go       Fake and the recursive renderer (choices, format strings, expansions)
-inline.go       inline templates: Template, NewTemplate, FakeTemplate, and their compile and link
 template.go     the {token} grammar: scanning, tokens, operands, validation, compiling a format
 hold.go         the hold: one draw per expansion for paths and operands, and its fences
 reference.go    reference sigils, and binding references across the tree
@@ -516,4 +435,4 @@ data/           shipped data (JSON), embedded at build: locale folders + a misc
 
 ## License
 
-MIT — see [LICENSE](LICENSE). Forked from [github.com/Timewave-AB/fakes](https://github.com/Timewave-AB/fakes).
+MIT — see [LICENSE](LICENSE).

builtins.go

@@ -2,7 +2,6 @@ package fejkdata
 
 import (
 	"encoding/base64"
-	"errors"
 	"fmt"
 	"math"
 	"strconv"
@@ -10,12 +9,12 @@ import (
 	"unicode"
 )
 
-// maxLen caps sample output lengths (hex, nanoid, base64, digits, upper, lower)
-// and maxDecimals float/calc decimal places, so a fat-fingered or overflowing
-// argument fails at New instead of trying to allocate gigabytes — or panicking —
-// at render.
+// maxLen caps sample output lengths (hex, nanoid, base64) and the renders a repeat
+// multiplies to along any path; maxDecimals caps float/calc decimal places. So a
+// fat-fingered or overflowing argument fails at New instead of trying to allocate
+// gigabytes — or panicking — at render.
 const (
-	maxLen      = 1 << 20
+	maxLen      = 1 << 20 // 1,048,576 chars/bytes
 	maxDecimals = 1024
 )
 
@@ -133,7 +132,7 @@ func transformArg(fields map[string]node, a []string) error {
 		_, _, err := refShape(leaf)
 		return err
 	}
-	return checkArm(leaf, fields, false)
+	return checkArm(leaf, fields)
 }
 
 func transformOperand(a []string) []string {
@@ -177,7 +176,7 @@ var asciiFolds = map[rune]string{
 func asciiFold(s string) string {
 	var b strings.Builder
 	for _, r := range s {
-		if r <= unicode.MaxASCII {
+		if r < unicode.MaxASCII {
 			b.WriteRune(r)
 		} else {
 			b.WriteString(asciiFolds[r])
@@ -222,31 +221,10 @@ func randChars(r rng, n int, alphabet string) string {
 	return string(b)
 }
 
-// plainInt parses an integer arg written the one way: no sign, no leading zero.
-func plainInt(s string) (int, error) {
-	n, err := strconv.Atoi(s)
-	if errors.Is(err, strconv.ErrRange) {
-		return 0, fmt.Errorf("%q is past the integer range: %w", s, err)
-	}
-	if err != nil {
-		return 0, fmt.Errorf("%q is not an integer", s)
-	}
-	if strconv.Itoa(n) != s {
-		return 0, fmt.Errorf("%q is not a plain integer; write %d", s, n)
-	}
-	return n, nil
-}
-
 func posIntArg(_ map[string]node, a []string) error {
-	n, err := plainInt(a[0])
-	if errors.Is(err, strconv.ErrRange) {
-		return fmt.Errorf("count %q exceeds the maximum %d", a[0], maxLen)
-	}
-	if err != nil {
-		return fmt.Errorf("count %w", err)
-	}
-	if n < 1 {
-		return fmt.Errorf("count %q must be positive", a[0])
+	n, err := strconv.Atoi(a[0])
+	if err != nil || n < 1 {
+		return fmt.Errorf("count %q must be a positive integer", a[0])
 	}
 	if n > maxLen {
 		return fmt.Errorf("count %d exceeds the maximum %d", n, maxLen)
@@ -255,20 +233,14 @@ func posIntArg(_ map[string]node, a []string) error {
 }
 
 func intRangeArgs(_ map[string]node, a []string) error {
-	lo, err := plainInt(a[0])
-	if err != nil {
-		return fmt.Errorf("int(min,max): min %w", err)
-	}
-	hi, err := plainInt(a[1])
-	if err != nil {
-		return fmt.Errorf("int(min,max): max %w", err)
+	lo, e1 := strconv.Atoi(a[0])
+	hi, e2 := strconv.Atoi(a[1])
+	if e1 != nil || e2 != nil {
+		return fmt.Errorf("int(min,max) needs integer args, got %q,%q", a[0], a[1])
 	}
 	if lo > hi {
 		return fmt.Errorf("int(min,max): min %d > max %d", lo, hi)
 	}
-	if lo == hi {
-		return fmt.Errorf("int(%d,%d) is the constant %d; write it as text", lo, hi, lo)
-	}
 	if uint64(hi)-uint64(lo) >= uint64(math.MaxInt64) { // span hi-lo+1 would overflow int -> IntN panic
 		return fmt.Errorf("int(min,max): range %d..%d is too wide", lo, hi)
 	}
@@ -278,28 +250,19 @@ func intRangeArgs(_ map[string]node, a []string) error {
 func floatArgs(_ map[string]node, a []string) error {
 	lo, e1 := strconv.ParseFloat(a[0], 64)
 	hi, e2 := strconv.ParseFloat(a[1], 64)
-	if e1 != nil || e2 != nil {
-		return fmt.Errorf("float(min,max,dp) needs numeric bounds, got %q,%q", a[0], a[1])
-	}
-	dp, err := plainInt(a[2])
-	if err != nil {
-		return fmt.Errorf("float(min,max,dp): decimals %w", err)
-	}
-	if math.IsNaN(lo) || math.IsNaN(hi) || math.IsInf(lo, 0) || math.IsInf(hi, 0) {
-		return fmt.Errorf("float(min,max,dp) needs finite bounds, got %q,%q", a[0], a[1])
+	dp, e3 := strconv.Atoi(a[2])
+	if e1 != nil || e2 != nil || e3 != nil {
+		return fmt.Errorf("float(min,max,dp) needs numeric args, got %q,%q,%q", a[0], a[1], a[2])
 	}
 	if lo > hi {
 		return fmt.Errorf("float(min,max,dp): min %v > max %v", lo, hi)
 	}
-	if dp < 0 || dp > maxDecimals {
-		return fmt.Errorf("float(min,max,dp): decimals %d out of range 0..%d", dp, maxDecimals)
-	}
-	if lo == hi {
-		return fmt.Errorf("float(%s,%s,%d) is the constant %q; write it as text", a[0], a[1], dp, strconv.FormatFloat(lo, 'f', dp, 64))
-	}
 	if math.IsInf(hi-lo, 0) { // an overflowing span would render as "+Inf"
 		return fmt.Errorf("float(min,max,dp): range %v..%v is too wide", lo, hi)
 	}
+	if dp < 0 || dp > maxDecimals {
+		return fmt.Errorf("float(min,max,dp): decimals %d out of range 0..%d", dp, maxDecimals)
+	}
 	return nil
 }
 

calc.go

@@ -78,82 +78,14 @@ func checkCalc(fields map[string]node, args []string) error {
 			return fmt.Errorf("calc(%q): operand %q is never a number: it renders %q", args[0], name, text)
 		}
 	}
-	if divisor, zero := constantZeroDivisor(expr, fields); zero {
-		return fmt.Errorf("calc(%q) divides by %s, which is always zero", args[0], divisor)
-	}
 	if len(args) == 2 {
-		dp, err := plainInt(args[1])
-		if err != nil {
-			return fmt.Errorf("calc decimals %w", err)
-		}
-		if dp < 0 || dp > maxDecimals {
-			return fmt.Errorf("calc decimals %d must be in 0..%d", dp, maxDecimals)
+		if dp, err := strconv.Atoi(args[1]); err != nil || dp < 0 || dp > maxDecimals {
+			return fmt.Errorf("calc decimals %q must be an integer in 0..%d", args[1], maxDecimals)
 		}
 	}
 	return nil
 }
 
-// constantZeroDivisor finds a division whose right side is a constant zero: number
-// literals and fixed operands folded, anything that varies left unknown.
-func constantZeroDivisor(n calcNode, fields map[string]node) (string, bool) {
-	switch n := n.(type) {
-	case calcNeg:
-		return constantZeroDivisor(n.x, fields)
-	case calcBin:
-		if n.op == '/' {
-			if v, known := constantValue(n.r, fields); known && v == 0 {
-				return calcText(n.r), true
-			}
-		}
-		if d, zero := constantZeroDivisor(n.l, fields); zero {
-			return d, true
-		}
-		return constantZeroDivisor(n.r, fields)
-	}
-	return "", false
-}
-
-// constantValue evaluates an expression whose every operand is fixed.
-func constantValue(n calcNode, fields map[string]node) (float64, bool) {
-	switch n := n.(type) {
-	case calcNum:
-		return float64(n), true
-	case calcVar:
-		t, ok := fields[string(n)].(*template)
-		if !ok || !t.fixed || t.repeat > 1 {
-			return 0, false
-		}
-		v, err := strconv.ParseFloat(strings.TrimSpace(t.lit), 64)
-		return v, err == nil
-	case calcNeg:
-		v, ok := constantValue(n.x, fields)
-		return -v, ok
-	case calcBin:
-		l, lok := constantValue(n.l, fields)
-		r, rok := constantValue(n.r, fields)
-		if !lok || !rok {
-			return 0, false
-		}
-		return calcBin{n.op, calcNum(l), calcNum(r)}.eval(nil), true
-	}
-	return 0, false
-}
-
-// calcText spells an expression node the way an author would read it.
-func calcText(n calcNode) string {
-	switch n := n.(type) {
-	case calcNum:
-		return strconv.FormatFloat(float64(n), 'f', -1, 64)
-	case calcVar:
-		return string(n)
-	case calcNeg:
-		return "-" + calcText(n.x)
-	case calcBin:
-		return "(" + calcText(n.l) + " " + string(n.op) + " " + calcText(n.r) + ")"
-	}
-	return "?"
-}
-
 // neverNumeric reports a node no render of which is a number: fixed text that does
 // not parse, or a choice of only such items. text is one such render.
 func neverNumeric(n node) (text string, never bool) {

calc_test.go

@@ -245,28 +245,3 @@ func TestCalcOverANeverNumericOperandIsRejected(t *testing.T) {
 		}
 	}
 }
-
-func TestCalcConstantZeroDivisorIsRejected(t *testing.T) {
-	for src, want := range map[string]string{
-		`"{calc(1/0)}"`:                                  "divides by 0",
-		`"{calc(2/(1-1))}"`:                              "divides by (1 - 1)",
-		`{"format":"{calc(x/y)}","x":"1","y":"0"}`:       "divides by y",
-		`{"format":"{calc(x/(y*2))}","x":"1","y":" 0 "}`: "divides by (y * 2)",
-		`{"format":"{calc((a/0)+b)}","a":"1","b":"2"}`:   "divides by 0",
-		`{"format":"{calc(a/-0)}","a":"1"}`:              "divides by -0",
-	} {
-		if _, err := compile(parse(t, src)); err == nil || !strings.Contains(err.Error(), want) {
-			t.Errorf("compile(%s) = %v, want the constant zero divisor rejected naming %q", src, err, want)
-		}
-	}
-	if _, err := compile(parse(t, `{"format":"{calc(a/(b*c))}","a":"1","b":"0","c":["1","2"]}`)); err != nil {
-		t.Errorf("compile(a/(b*c)) = %v, want a divisor that varies accepted", err)
-	}
-	f := engine(1)
-	for i := 0; i < 50; i++ {
-		if got := mustRender(t, f, `{"format":"{calc(x/y)}","x":"1","y":["0","1"]}`); got == "+Inf" {
-			return
-		}
-	}
-	t.Fatal("a sometimes-zero divisor never printed +Inf in 50 draws")
-}

cmd/fejkdata/main.go

@@ -8,8 +8,6 @@
 package main
 
 import (
-	"bufio"
-	"encoding/json"
 	"errors"
 	"fmt"
 	"io"
@@ -21,45 +19,34 @@ import (
 	"gitea.larvit.se/larvit/fejkdata"
 )
 
-const usage = `Usage: fejkdata [flags] <path|template>
+const usage = `Usage: fejkdata [flags] <path>
 
   <path>                 a category, or a dotted path into one (person, person.last)
-  <template>             a format string or JSON value to render inline, e.g.
-                         'name: {/sv_SE.person.last}' or '{"format":"{x}","x":["bosse","lina"]}'
-
-An argument containing a { token, or a JSON object, array or string, is a
-template; any other argument is a path (a path never contains a brace, a bracket
-or a quote). Templates reach the data by reference from the root —
-{/sv_SE.person.last} — whether the data is shipped or layered with --data-path. An
-argument carrying a bracket, a closing brace or a quote but no valid JSON names
-neither.
 
   -d, --data-path D      a data directory to layer over the shipped data (repeatable; last wins on a clash)
   -h, --help             print this help, then exit
       --list             list the paths the data offers, then exit
       --no-shipped-data  load only the --data-path directories
-  -n, --repeat N         render the value N times, 1..1048576 (default 1)
+  -n, --repeat N         render the path N times (default 1)
   -s, --seed N           seed for reproducible output
       --separator S      string between repeated values (default newline)
       --version          print the version, then exit
 
-Flags may come before or after <path|template>; -- ends the flags. A short flag's
-value attaches or follows (-n3, -n 3); short flags bundle (-hn 3).
+Flags may come before or after <path>; -- ends the flags. A short flag's value
+attaches or follows (-n3, -n 3); short flags bundle (-hn 3).
 `
 
 type invocation struct {
-	dirs         []string
-	help         bool
-	list         bool
-	noShipped    bool
-	paths        []string
-	repeat       int
-	repeatSet    bool
-	seed         uint64
-	seeded       bool
-	separator    string
-	separatorSet bool
-	version      bool
+	dirs      []string
+	help      bool
+	list      bool
+	noShipped bool
+	paths     []string
+	repeat    int
+	seed      uint64
+	seeded    bool
+	separator string
+	version   bool
 }
 
 type flagDef struct {
@@ -76,10 +63,10 @@ var flagDefs = []flagDef{
 	{"no-shipped-data", "", false, func(in *invocation, _ string) error { in.noShipped = true; return nil }},
 	{"repeat", "n", true, func(in *invocation, v string) error {
 		n, err := strconv.Atoi(v)
-		if err != nil || n < 1 || n > fejkdata.MaxRepeat {
-			return fmt.Errorf("--repeat needs an integer in 1..%d, got %q", fejkdata.MaxRepeat, v)
+		if err != nil || n < 1 {
+			return fmt.Errorf("--repeat needs a positive integer, got %q", v)
 		}
-		in.repeat, in.repeatSet = n, true
+		in.repeat = n
 		return nil
 	}},
 	{"seed", "s", true, func(in *invocation, v string) error {
@@ -90,7 +77,7 @@ var flagDefs = []flagDef{
 		in.seed, in.seeded = n, true
 		return nil
 	}},
-	{"separator", "", true, func(in *invocation, v string) error { in.separator, in.separatorSet = v, true; return nil }},
+	{"separator", "", true, func(in *invocation, v string) error { in.separator = v; return nil }},
 	{"version", "", false, func(in *invocation, _ string) error { in.version = true; return nil }},
 }
 
@@ -137,8 +124,8 @@ func splitFlags(arg string) ([]flagArg, error) {
 	}
 	var flags []flagArg
 	letters := arg[1:]
-	for i, r := range letters {
-		letter := string(r)
+	for i := 0; i < len(letters); i++ {
+		letter := letters[i : i+1]
 		def := flagByShort(letter)
 		if def == nil {
 			return nil, fmt.Errorf("unknown flag -%s", letter)
@@ -147,7 +134,7 @@ func splitFlags(arg string) ([]flagArg, error) {
 			flags = append(flags, flagArg{def: def})
 			continue
 		}
-		rest := letters[i+len(letter):]
+		rest := letters[i+1:]
 		if strings.HasPrefix(rest, "=") {
 			return nil, fmt.Errorf("-%s takes its value attached (-%s%s) or next (-%s %s); = belongs to --%s=%s",
 				letter, letter, rest[1:], letter, rest[1:], def.long, rest[1:])
@@ -196,22 +183,15 @@ func parseArgs(argv []string) (invocation, error) {
 	return in, nil
 }
 
-// check rejects a flag combination or an argument that cannot run, and reports
-// what the argument names, so its shape is settled before any data is read.
-func (in invocation) check() (argKind, error) {
+// check rejects a flag combination that cannot run.
+func (in invocation) check() error {
 	if in.list && len(in.paths) > 0 {
-		return argPath, errors.New("--list takes no path")
+		return errors.New("--list takes no path")
 	}
-	if in.list && (in.repeatSet || in.separatorSet) {
-		return argPath, errors.New("--list takes no --repeat or --separator")
+	if !in.list && len(in.paths) != 1 {
+		return fmt.Errorf("expected one path, got %d", len(in.paths))
 	}
-	if in.list {
-		return argPath, nil
-	}
-	if len(in.paths) != 1 {
-		return argPath, fmt.Errorf("expected one path or template, got %d", len(in.paths))
-	}
-	return classify(in.paths[0])
+	return nil
 }
 
 func (in invocation) options() []fejkdata.Option {
@@ -228,63 +208,17 @@ func (in invocation) options() []fejkdata.Option {
 	return opts
 }
 
-// write streams the argument's renders to w, repeat of them joined by the
-// separator and ended by a newline. A value that renders once renders every time,
-// so a render failure comes before anything is written; a write failure surfaces
-// from Flush, bufio keeping the first one.
-func (in invocation) write(f *fejkdata.Generator, kind argKind, w io.Writer) error {
-	arg := in.paths[0]
-	draw := func() (string, error) { return f.Fake(arg) }
-	if kind == argTemplate {
-		t, err := f.NewTemplate(arg)
+// values renders the path repeat times, joined by the separator.
+func (in invocation) values(f *fejkdata.Generator) (string, error) {
+	vals := make([]string, in.repeat)
+	for i := range vals {
+		v, err := f.Fake(in.paths[0])
 		if err != nil {
-			return templateError{err}
+			return "", err
 		}
-		draw = func() (string, error) { return t.Fake(), nil }
+		vals[i] = v
 	}
-	out := bufio.NewWriter(w)
-	for i := 0; i < in.repeat; i++ {
-		v, err := draw()
-		if err != nil {
-			return err
-		}
-		if i > 0 {
-			out.WriteString(in.separator)
-		}
-		out.WriteString(v)
-	}
-	out.WriteString("\n")
-	return out.Flush()
-}
-
-// templateError marks a render failure that is the argument's own fault — an
-// inline template that does not compile. run reports it as misuse (exit 2, with a
-// pointer to --help), unlike an unknown path, which is a runtime error (exit 1).
-type templateError struct{ error }
-
-func (e templateError) Unwrap() error { return e.error }
-
-type argKind int
-
-const (
-	argPath argKind = iota
-	argTemplate
-)
-
-// classify reads what a positional argument names by its shape: a { token, or a
-// JSON object, array or string, is an inline template; anything else is a path.
-func classify(arg string) (argKind, error) {
-	if strings.ContainsRune(arg, '{') || (isJSONStart(strings.TrimSpace(arg)) && json.Valid([]byte(arg))) {
-		return argTemplate, nil
-	}
-	if i := strings.IndexAny(arg, `[]}"`); i >= 0 {
-		return argPath, fmt.Errorf("%q holds a %q, which no path may, and it is not valid JSON, so it names no template either", arg, arg[i:i+1])
-	}
-	return argPath, nil
-}
-
-func isJSONStart(arg string) bool {
-	return strings.HasPrefix(arg, "[") || strings.HasPrefix(arg, `"`)
+	return strings.Join(vals, in.separator), nil
 }
 
 func main() { os.Exit(run(os.Args[1:], os.Stdout, os.Stderr)) }
@@ -303,8 +237,7 @@ func run(args []string, stdout, stderr io.Writer) int {
 		fmt.Fprintln(stdout, "fejkdata "+buildVersion())
 		return 0
 	}
-	kind, err := in.check()
-	if err != nil {
+	if err := in.check(); err != nil {
 		return misuse(stderr, err)
 	}
 	f, err := fejkdata.New(in.options()...)
@@ -321,20 +254,17 @@ func run(args []string, stdout, stderr io.Writer) int {
 		}
 		return 0
 	}
-	if err := in.write(f, kind, stdout); err != nil {
-		var te templateError
-		if errors.As(err, &te) {
-			return misuse(stderr, te.error)
-		}
+	out, err := in.values(f)
+	if err != nil {
 		fmt.Fprintln(stderr, err)
 		return 1
 	}
+	fmt.Fprintln(stdout, out)
 	return 0
 }
 
 func misuse(stderr io.Writer, err error) int {
-	// A library error already names the program, so the prefix is not doubled.
-	fmt.Fprintf(stderr, "fejkdata: %s\ntry 'fejkdata --help'\n", strings.TrimPrefix(err.Error(), "fejkdata: "))
+	fmt.Fprintf(stderr, "fejkdata: %v\ntry 'fejkdata --help'\n", err)
 	return 2
 }
 

cmd/fejkdata/main_test.go

@@ -4,7 +4,6 @@ import (
 	"bytes"
 	"os"
 	"path/filepath"
-	"regexp"
 	"strings"
 	"testing"
 )
@@ -93,7 +92,7 @@ func TestRunShortFlagValues(t *testing.T) {
 		{[]string{"-s=42", "-d", svSE, "address"}, "-s42"},
 		{[]string{"-s=42", "-d", svSE, "address"}, "--seed=42"},
 		{[]string{"-d=" + svSE, "address"}, "--data-path="},
-		{[]string{"-nd", "3", "-d", svSE, "word"}, `--repeat needs an integer in 1..1048576, got "d"`},
+		{[]string{"-nd", "3", "-d", svSE, "word"}, `--repeat needs a positive integer, got "d"`},
 		{[]string{"--seed=", "-d", svSE, "word"}, `--seed needs an unsigned integer, got ""`},
 	} {
 		code, out, errb := runOut(c.args...)
@@ -302,92 +301,6 @@ func TestRunShippedDataByDefault(t *testing.T) {
 	}
 }
 
-func TestClassify(t *testing.T) {
-	for arg, want := range map[string]argKind{
-		"sv_SE.person":   argPath,
-		"person.last":    argPath,
-		"name: {x}":      argTemplate, // a { token: a path can never carry a brace
-		`{"format":"x"}`: argTemplate,
-		`["a","b"]`:      argTemplate, // a JSON array carries no brace
-		`[1, 2]`:         argTemplate,
-		` ["a","b"]`:     argTemplate, // padding is the template's own error, not a shape verdict
-		`"hello"`:        argTemplate, // a JSON string, the spelling a format-only object names
-	} {
-		got, err := classify(arg)
-		if err != nil || got != want {
-			t.Errorf("classify(%q) = %v, %v; want %v", arg, got, err, want)
-		}
-	}
-	for arg, want := range map[string]string{
-		"[abc]":       `holds a "["`,
-		"[abc].field": `holds a "["`,
-		"x[1]":        `holds a "["`,
-		"a]b":         `holds a "]"`,
-		"a}b":         `holds a "}"`,
-		`"abc`:        `holds a "\""`,
-		`"a]b`:        `holds a "\""`, // the opener the reader typed, not the bracket behind it
-	} {
-		_, err := classify(arg)
-		if err == nil || !strings.Contains(err.Error(), want) {
-			t.Errorf("classify(%q) = %v; want it rejected naming %s", arg, err, want)
-		}
-	}
-}
-
-func TestUsageReferencesResolve(t *testing.T) {
-	for _, token := range regexp.MustCompile(`\{/[^}]+\}`).FindAllString(usage, -1) {
-		code, out, errb := runOut("--seed", "1", token)
-		if code != 0 || strings.TrimSpace(out) == "" {
-			t.Errorf("usage advertises %s: run = %d, %q, stderr %q", token, code, out, errb)
-		}
-	}
-}
-
-func TestRunShapeMisuseBeforeLoad(t *testing.T) {
-	code, _, errb := runOut("--no-shipped-data", "[abc]")
-	if code != 2 || !strings.Contains(errb, "[abc]") || strings.Contains(errb, "--data-path") {
-		t.Fatalf("shape misuse with no data = %d, %q; want the shape error before any load", code, errb)
-	}
-}
-
-func TestRunInlineTemplate(t *testing.T) {
-	code, out, errb := runOut("--seed", "1", "name: {/sv_SE.person.last}")
-	if code != 0 || !strings.HasPrefix(out, "name: ") || strings.Contains(out, "{") {
-		t.Fatalf("inline format string = %d, %q, stderr %q", code, out, errb)
-	}
-	code, out, errb = runOut("--seed", "1", `{"format":"name: {x}","x":["bosse","lina"]}`)
-	if code != 0 || (out != "name: bosse\n" && out != "name: lina\n") {
-		t.Fatalf("inline JSON template = %d, %q, want one name, stderr %q", code, out, errb)
-	}
-	code, out, errb = runOut("--seed", "1", `"name: {/sv_SE.person.last}"`)
-	if code != 0 || !strings.HasPrefix(out, "name: ") || strings.Contains(out, "{") {
-		t.Fatalf("inline JSON string = %d, %q, stderr %q", code, out, errb)
-	}
-	code, out, errb = runOut("--seed", "1", "-n", "2", `{digits(1)}`)
-	if code != 0 || len(strings.Split(strings.TrimRight(out, "\n"), "\n")) != 2 {
-		t.Fatalf("inline template with --repeat = %d, %q, stderr %q", code, out, errb)
-	}
-}
-
-func TestRunTemplateMisuse(t *testing.T) {
-	for arg, want := range map[string]string{
-		"{bad":            "unterminated",
-		"[red,green]":     "names no template either",
-		`{"format":"x"}`:  "is a string",
-		"{/no.such.path}": "no entry",
-		"x[1]":            "names no template either",
-		` ["a","b"] `:     "may not be padded",
-	} {
-		code, out, errb := runOut("--seed", "1", arg)
-		if code != 2 || out != "" || !strings.Contains(errb, "try 'fejkdata --help'") || !strings.Contains(errb, want) {
-			t.Errorf("run(%q) = %d, %q, %q; want misuse naming %q and --help", arg, code, out, errb, want)
-		}
-		if strings.Contains(errb, "fejkdata: fejkdata:") {
-			t.Errorf("run(%q) doubled the program prefix: %q", arg, errb)
-		}
-	}
-}
-
 func TestRunNoShippedData(t *testing.T) {
 	code, list, errb := runOut("--no-shipped-data", "-d", svSE, "--list")
 	if code != 0 {
@@ -442,18 +355,3 @@ func TestRunUnknownFlagIsNamedByRune(t *testing.T) {
 		t.Errorf("run(-ä) = %d, %q, want the flag named whole", code, errb)
 	}
 }
-
-func TestRunEmptyDataPathIsNamed(t *testing.T) {
-	code, _, errb := runOut("--data-path=", "sv_SE.word")
-	if code != 1 || !strings.Contains(errb, "empty") {
-		t.Errorf("run(--data-path=) = %d, %q, want the empty path named", code, errb)
-	}
-}
-
-func TestRunNumbersFollowTheShell(t *testing.T) {
-	_, want, _ := runOut("--seed", "7", "--repeat", "3", "sv_SE.word")
-	code, got, errb := runOut("--seed", "007", "--repeat", "+3", "sv_SE.word")
-	if code != 0 || got != want {
-		t.Errorf("run(--seed 007 --repeat +3) = %d, %q, stderr %q; want the same as --seed 7 --repeat 3 %q", code, got, errb, want)
-	}
-}

data.go

@@ -10,14 +10,13 @@ import (
 )
 
 // dataSource is one tree to load: an fs.FS and the directory in it to start from.
-// label prefixes file names in errors; onDisk marks path as a directory that must
-// exist.
+// label prefixes file names in errors; path, when set, is a directory on disk that
+// must exist.
 type dataSource struct {
-	fsys   fs.FS
-	label  string
-	onDisk bool
-	path   string
-	root   string
+	fsys  fs.FS
+	label string
+	path  string
+	root  string
 }
 
 func (s dataSource) name(p string) string {
@@ -37,13 +36,10 @@ func (s dataSource) name(p string) string {
 func loadData(sources []dataSource) (map[string]node, error) {
 	root := map[string]node{}
 	for _, src := range sources {
-		if src.onDisk {
-			if src.path == "" {
-				return nil, fmt.Errorf("a data path is empty")
-			}
+		if src.path != "" {
 			info, err := os.Stat(src.path)
 			if err != nil {
-				return nil, err
+				return nil, fmt.Errorf("%s: no such directory", src.path)
 			}
 			if !info.IsDir() {
 				return nil, fmt.Errorf("%s is not a directory", src.path)
@@ -68,7 +64,10 @@ func loadData(sources []dataSource) (map[string]node, error) {
 	if err := checkNoCycles(root); err != nil {
 		return nil, err
 	}
-	if err := checkScope(treeScope(root)); err != nil {
+	if err := checkRepeatReach(root); err != nil {
+		return nil, err
+	}
+	if err := checkBoundLevelsHeld(root); err != nil {
 		return nil, err
 	}
 	return root, nil

fejkdata.go

@@ -28,19 +28,12 @@ import (
 //go:embed data
 var shippedFS embed.FS
 
-// MaxRepeat caps a repeat, and the renders nested repeats multiply to along any
-// path; the CLI's --repeat shares it.
-const MaxRepeat = 1 << 20
-
-var _ [^uint(0)>>63 - 1]struct{} // 64-bit only, per the README's Decisions
-
 // ErrNoData is returned by New when no source is loaded at all.
 var ErrNoData = errors.New("no data: WithoutShippedData needs at least one WithDataPath or WithDataFS")
 
 // Generator generates fake data from a loaded namespace tree. Create one with [New].
 // It is safe for concurrent use; a seeded sequence is reproducible only when drawn
-// from one goroutine. The compiled tree is immutable after [New], and Fake,
-// NewTemplate and List read it concurrently without a lock.
+// from one goroutine.
 type Generator struct {
 	mu         sync.Mutex
 	rand       *session
@@ -79,7 +72,7 @@ func WithSeed(seed uint64) Option {
 // layer several; the last wins a name clash.
 func WithDataPath(dir string) Option {
 	return func(c *config) {
-		c.sources = append(c.sources, dataSource{fsys: os.DirFS(dir), label: dir, onDisk: true, path: dir})
+		c.sources = append(c.sources, dataSource{fsys: os.DirFS(dir), label: dir, path: dir})
 	}
 }
 
@@ -116,11 +109,7 @@ func New(opts ...Option) (*Generator, error) {
 	if err != nil {
 		return nil, fmt.Errorf("fejkdata: %w", err)
 	}
-	rng, err := newRand(c.seed, c.seeded)
-	if err != nil {
-		return nil, fmt.Errorf("fejkdata: %w", err)
-	}
-	return &Generator{rand: rng, categories: cats}, nil
+	return &Generator{rand: newRand(c.seed, c.seeded), categories: cats}, nil
 }
 
 // List returns the sorted dotted paths Fake can render: every category, the dotted
@@ -211,19 +200,12 @@ func join(prefix, name string) string {
 	return prefix + "." + name
 }
 
-// randomBytes seeds an unseeded generator.
-var randomBytes = crand.Read
-
-func newRand(seed uint64, seeded bool) (*session, error) {
-	var r *rand.Rand
-	if seeded {
-		r = rand.New(rand.NewPCG(seed, seed^0x9e3779b97f4a7c15))
-	} else {
+func newRand(seed uint64, seeded bool) *session {
+	r := rand.New(rand.NewPCG(seed, seed^0x9e3779b97f4a7c15))
+	if !seeded {
 		var b [16]byte
-		if _, err := randomBytes(b[:]); err != nil {
-			return nil, fmt.Errorf("seeding from crypto/rand: %w", err)
-		}
+		_, _ = crand.Read(b[:])
 		r = rand.New(rand.NewPCG(binary.LittleEndian.Uint64(b[:8]), binary.LittleEndian.Uint64(b[8:])))
 	}
-	return &session{Rand: r, counters: map[string]uint64{}}, nil
+	return &session{Rand: r, counters: map[string]uint64{}}
 }

fejkdata_test.go

@@ -1,11 +1,8 @@
 package fejkdata
 
 import (
-	"errors"
-	"io/fs"
 	"strings"
 	"testing"
-	"testing/fstest"
 )
 
 // newGenerator creates a generator over a single data directory, failing on
@@ -41,25 +38,8 @@ func fake(t *testing.T, f *Generator, path string) string {
 
 func TestNewMissingDirectory(t *testing.T) {
 	_, err := New(WithoutShippedData(), WithDataPath("data/de_DE"))
-	if err == nil || !strings.Contains(err.Error(), "de_DE") || !errors.Is(err, fs.ErrNotExist) {
-		t.Fatalf("New(missing) error = %v, want the real error, naming the path", err)
-	}
-}
-
-func TestNewRejectsAnEmptyDataPath(t *testing.T) {
-	_, err := New(WithoutShippedData(), WithDataPath(""))
-	if err == nil || !strings.Contains(err.Error(), "empty") {
-		t.Fatalf("New(WithDataPath(\"\")) = %v, want the empty path named", err)
-	}
-}
-
-func TestNewReportsAnEntropyFailure(t *testing.T) {
-	saved := randomBytes
-	randomBytes = func([]byte) (int, error) { return 0, errors.New("no entropy") }
-	defer func() { randomBytes = saved }()
-	_, err := New(WithoutShippedData(), WithDataFS(fstest.MapFS{"w.json": {Data: []byte(`"x"`)}}))
-	if err == nil || !strings.Contains(err.Error(), "no entropy") {
-		t.Fatalf("New() without entropy = %v, want the failure reported", err)
+	if err == nil || !strings.Contains(err.Error(), "de_DE") {
+		t.Fatalf("New(missing) error = %v, want it to name the path", err)
 	}
 }
 

graph.go

@@ -10,36 +10,29 @@ import (
 // visiting keys in sorted order so which of several broken nodes gets reported does
 // not depend on map iteration.
 func walkNodes(root map[string]node, fn func(path string, n node) error) error {
-	for _, name := range sortedNames(root) {
-		if err := eachNode(root[name], name, fn); err != nil {
-			return err
-		}
-	}
-	return nil
-}
-
-// eachNode visits n and every node contained within it once, passing the dot path
-// that reaches each. It never crosses a reference edge — a bound {/path} field is
-// skipped — so a single inline node is walked on its own.
-func eachNode(n node, path string, fn func(path string, n node) error) error {
 	seen := map[node]bool{}
 	var visit func(string, node) error
-	visit = func(path string, m node) error {
-		if m == nil || seen[m] {
+	visit = func(path string, n node) error {
+		if n == nil || seen[n] {
 			return nil
 		}
-		seen[m] = true
-		if err := fn(path, m); err != nil {
+		seen[n] = true
+		if err := fn(path, n); err != nil {
 			return err
 		}
-		for _, c := range contained(m) {
+		for _, c := range contained(n) {
 			if err := visit(join(path, c.name), c.node); err != nil {
 				return err
 			}
 		}
 		return nil
 	}
-	return visit(path, n)
+	for _, name := range sortedNames(root) {
+		if err := visit(name, root[name]); err != nil {
+			return err
+		}
+	}
+	return nil
 }
 
 // namedNode is a contained child and the segment reaching it; a choice's items carry
@@ -165,56 +158,34 @@ func pathLeaves(n node, tail []string) []node {
 	return out
 }
 
-// nodeScope is the set of nodes one validation pass covers: a whole loaded tree,
-// or a single inline node.
-type nodeScope func(fn func(path string, n node) error) error
-
-func treeScope(root map[string]node) nodeScope {
-	return func(fn func(path string, n node) error) error { return walkNodes(root, fn) }
-}
-
-func inlineScope(n node) nodeScope {
-	return func(fn func(path string, m node) error) error { return eachNode(n, "template", fn) }
-}
-
-// checkScope runs the per-node fences over a scope, each over the whole scope
-// before the next, so which of several broken nodes is reported does not depend on
-// the walk. It runs after checkNoCycles, whose guarantee is what lets the walks
-// terminate.
-func checkScope(s nodeScope) error {
-	mem := reachMemo{}
-	if err := s(func(path string, n node) error { return repeatCheck(path, n, mem) }); err != nil {
-		return err
-	}
-	return s(heldCheck)
-}
-
-type reachMemo map[node]int
-
-func (m reachMemo) of(n node) int {
-	if r, done := m[n]; done {
+// checkRepeatReach bounds the renders a repeat multiplies to along any root-to-leaf
+// path, so nested repeats cannot build what one repeat may not. It runs after
+// checkNoCycles, whose guarantee is what lets the walk terminate.
+func checkRepeatReach(root map[string]node) error {
+	reach := map[node]int{}
+	var of func(n node) int
+	of = func(n node) int {
+		if r, done := reach[n]; done {
+			return r
+		}
+		r := 1
+		for _, e := range renderEdges(n) {
+			if c := of(e.to); c > r {
+				r = c
+			}
+		}
+		if t, ok := n.(*template); ok {
+			r *= t.repeat
+		}
+		reach[n] = r
 		return r
 	}
-	r := 1
-	for _, e := range renderEdges(n) {
-		if c := m.of(e.to); c > r {
-			r = c
+	return walkNodes(root, func(path string, n node) error {
+		if t, ok := n.(*template); ok && t.repeat > 1 && of(n) > maxLen {
+			return fmt.Errorf("%s: repeat %d multiplies to %d renders along one path, above the maximum %d", path, t.repeat, of(n), maxLen)
 		}
-	}
-	if t, ok := n.(*template); ok {
-		r *= t.repeat
-	}
-	m[n] = r
-	return r
-}
-
-// repeatCheck bounds the renders a repeat multiplies to along any root-to-leaf
-// path, so nested repeats cannot build what one repeat may not.
-func repeatCheck(path string, n node, mem reachMemo) error {
-	if t, ok := n.(*template); ok && t.repeat > 1 && mem.of(n) > MaxRepeat {
-		return fmt.Errorf("%s: repeat %d multiplies to %d renders along one path, above the maximum %d", path, t.repeat, mem.of(n), MaxRepeat)
-	}
-	return nil
+		return nil
+	})
 }
 
 // checkNoCycles rejects a reference cycle: a node whose rendering can reach itself

hold.go

@@ -6,23 +6,27 @@ import (
 	"strings"
 )
 
-// heldCheck rejects every route to a held name except the ones that read its draw.
-// An expansion holds one draw of that name; anything else that renders it draws
-// again, and the two disagree. checkNoOverlap settles the spellings within one
+// checkBoundLevelsHeld rejects every route to a held name except the ones that read
+// its draw. An expansion holds one draw of that name; anything else that renders it
+// draws again, and the two disagree. checkNoOverlap settles the spellings within one
 // format (a token, an operand); this settles the rest — a reference, whether it
 // sits in that format or in anything the format renders, however deep.
-func heldCheck(path string, n node) error {
-	t, ok := n.(*template)
-	if !ok || len(t.held) == 0 {
-		return nil
-	}
-	readers := boundReaders(t.format, t.bound, t.refs)
-	for _, head := range heldHeads(t) {
-		if err := checkHeadHeld(t, head, readers); err != nil {
-			return fmt.Errorf("%s: %w", path, err)
+//
+// It runs after checkNoCycles, whose guarantee is what lets the walk terminate.
+func checkBoundLevelsHeld(root map[string]node) error {
+	return walkNodes(root, func(path string, n node) error {
+		t, ok := n.(*template)
+		if !ok || len(t.held) == 0 {
+			return nil
 		}
-	}
-	return nil
+		readers := boundReaders(t.format, t.bound, t.refs)
+		for _, head := range heldHeads(t) {
+			if err := checkHeadHeld(t, head, readers); err != nil {
+				return fmt.Errorf("%s: %w", path, err)
+			}
+		}
+		return nil
+	})
 }
 
 // heldHeads lists a template's held names, operand heads first, then paths, each
@@ -269,9 +273,6 @@ type draws struct {
 // linkRefs prove every step, so the walk cannot fail.
 func readField(s *session, t *template, held *draws, a arm) string {
 	if !t.held[a.key] {
-		if len(a.tail) > 0 {
-			panic(fmt.Sprintf("fejkdata: %q reads a path into %q, which the expansion does not hold", a.name, a.key))
-		}
 		return render(s, t.fields[a.key])
 	}
 	if v, read := held.value[a.path]; read {

hold_test.go

@@ -711,13 +711,3 @@ func TestRepeatedBareTokenOfAHeldNameIsRejected(t *testing.T) {
 		}
 	}
 }
-
-func TestReadFieldPanicsOnAnUnheldPath(t *testing.T) {
-	tm, ok := compiled(t, `{"format":"{w}","w":{"format":"{x}","x":"1"}}`).(*template)
-	if !ok {
-		t.Fatal("not a template")
-	}
-	mustPanic(t, "unheld arm with a path", func() {
-		readField(engine(1).rand, tm, nil, arm{name: "w.x", key: "w", tail: []string{"x"}, path: "w.x"})
-	})
-}

inline.go

@@ -1,88 +0,0 @@
-package fejkdata
-
-import (
-	"encoding/json"
-	"fmt"
-	"strings"
-)
-
-// Template is an inline template compiled, referenced and validated against a
-// generator's loaded data once, ready to render many times with [Template.Fake].
-// It is safe for concurrent use: Fake serializes on its generator's lock, so a
-// seeded sequence is reproducible only when a generator — and its templates — are
-// drawn from one goroutine.
-type Template struct {
-	g *Generator
-	n node
-}
-
-// Fake renders the template with one draw.
-func (t *Template) Fake() string {
-	t.g.mu.Lock()
-	defer t.g.mu.Unlock()
-	return render(t.g.rand, t.n)
-}
-
-// NewTemplate compiles an inline template — a format string or a JSON value — and
-// binds its references against the loaded tree, so repeated renders pay the
-// compile and validation once. It shares [New]'s guarantees: a bad template errors
-// here, and rendering cannot fail.
-func (f *Generator) NewTemplate(input string) (*Template, error) {
-	n, err := compileInput(input)
-	if err != nil {
-		return nil, fmt.Errorf("fejkdata: %w", err)
-	}
-	scope := inlineScope(n)
-	if err := linkNodeRefs(scope, f.categories); err != nil {
-		return nil, fmt.Errorf("fejkdata: %w", err)
-	}
-	if err := checkScope(scope); err != nil {
-		return nil, fmt.Errorf("fejkdata: %w", err)
-	}
-	return &Template{g: f, n: n}, nil
-}
-
-// FakeTemplate compiles and renders an inline template in one call. It is
-// [NewTemplate] then [Template.Fake]; to render the same template many times, hold
-// the *Template and call its Fake.
-func (f *Generator) FakeTemplate(input string) (string, error) {
-	t, err := f.NewTemplate(input)
-	if err != nil {
-		return "", err
-	}
-	return t.Fake(), nil
-}
-
-// compileInput compiles an inline template: a JSON value, or a bare format string
-// when the input is not JSON.
-func compileInput(input string) (node, error) {
-	var raw any
-	if err := json.Unmarshal([]byte(input), &raw); err != nil {
-		return compile(input)
-	}
-	if trimmed := strings.TrimSpace(input); trimmed != input {
-		return nil, fmt.Errorf("a JSON template may not be padded with spaces, which a format string would render; write %s", trimmed)
-	}
-	return compile(raw)
-}
-
-// linkNodeRefs binds the references in an inline node's templates against the
-// loaded tree.
-func linkNodeRefs(scope nodeScope, root map[string]node) error {
-	return scope(func(path string, m node) error {
-		t, ok := m.(*template)
-		if !ok {
-			return nil
-		}
-		for _, name := range refTokens(t.format) {
-			sigil, rest, err := refShape(name)
-			if err != nil {
-				return fmt.Errorf("%s: reference {%s}: %w", path, name, err)
-			}
-			if sigil != "/" {
-				return fmt.Errorf("%s: reference {%s}: an inline template has no folder; write {/%s}", path, name, rest)
-			}
-		}
-		return linkTemplateRefs(nil, path, t, root)
-	})
-}

inline_test.go

@@ -1,159 +0,0 @@
-package fejkdata
-
-import (
-	"strings"
-	"testing"
-)
-
-func tmpl(t *testing.T, f *Generator, input string) string {
-	t.Helper()
-	s, err := f.FakeTemplate(input)
-	if err != nil {
-		t.Fatalf("FakeTemplate(%q): %v", input, err)
-	}
-	return s
-}
-
-func shipped(t *testing.T, opts ...Option) *Generator {
-	t.Helper()
-	f, err := New(append([]Option{WithSeed(1)}, opts...)...)
-	if err != nil {
-		t.Fatal(err)
-	}
-	return f
-}
-
-func TestFakeTemplateFormatString(t *testing.T) {
-	f := shipped(t)
-	got := tmpl(t, f, "name: {/sv_SE.person.last}")
-	if !strings.HasPrefix(got, "name: ") || strings.HasSuffix(got, " ") || strings.Contains(got, "{") {
-		t.Fatalf("FakeTemplate = %q, want a rendered last name after the prefix", got)
-	}
-}
-
-func TestFakeTemplateJSONObject(t *testing.T) {
-	f := shipped(t)
-	seen := map[string]bool{}
-	for i := 0; i < 50; i++ {
-		seen[tmpl(t, f, `{"format":"name: {x}","x":["bosse","lina"]}`)] = true
-	}
-	if !seen["name: bosse"] || !seen["name: lina"] || len(seen) != 2 {
-		t.Fatalf("JSON template produced %v, want both names", seen)
-	}
-}
-
-func TestFakeTemplateJSONArray(t *testing.T) {
-	f := shipped(t)
-	seen := map[string]bool{}
-	for i := 0; i < 50; i++ {
-		seen[tmpl(t, f, `["foo","bar","baz"]`)] = true
-	}
-	if len(seen) != 3 {
-		t.Fatalf("JSON array choice produced %v, want three items", seen)
-	}
-}
-
-func TestFakeTemplateCorrelatedReferences(t *testing.T) {
-	dir := writeData(t, map[string]string{
-		"person": `[{"format":"{first} {last}","first":"Ada","last":"Lovelace"},{"format":"{first} {last}","first":"Bo","last":"Ek"}]`,
-	})
-	f := newGenerator(t, dir, WithSeed(1))
-	for i := 0; i < 100; i++ {
-		got := tmpl(t, f, "{/person.first} {/person.last}")
-		if got != "Ada Lovelace" && got != "Bo Ek" {
-			t.Fatalf("correlated references = %q, want one person's first and last", got)
-		}
-	}
-}
-
-func TestFakeTemplateDeterministic(t *testing.T) {
-	a, b := shipped(t), shipped(t)
-	for i := 0; i < 20; i++ {
-		in := "row: {/misc.uuid} {digits(3)}"
-		if x, y := tmpl(t, a, in), tmpl(t, b, in); x != y {
-			t.Fatalf("same seed diverged: %q != %q", x, y)
-		}
-	}
-}
-
-func TestFieldlessTokenHint(t *testing.T) {
-	f := shipped(t)
-	_, err := f.FakeTemplate(`{sv_SE.person.last}`)
-	if err == nil || !strings.Contains(err.Error(), "write {/sv_SE.person.last}") {
-		t.Fatalf("FakeTemplate(bare token) = %v, want a hint naming {/sv_SE.person.last}", err)
-	}
-	_, err = f.FakeTemplate(`{"format":"{x}","repeat":2}`)
-	if err == nil || !strings.Contains(err.Error(), `this template has none — write {/x}`) {
-		t.Errorf("FakeTemplate(fieldless object) = %v, want the hint without calling it a bare string", err)
-	}
-	// A hint is only a drop-in where the name is the whole token: {/x} inside a
-	// transform or an alternation renders a different value, so none is offered.
-	for _, input := range []string{`{ /sv_SE.person.last }`, "{lowercase(x)}", "{x|y}"} {
-		_, err := f.FakeTemplate(input)
-		if err == nil || strings.Contains(err.Error(), "write {") {
-			t.Errorf("FakeTemplate(%q) = %v, want no hint naming a spelling that means something else", input, err)
-		}
-	}
-}
-
-func TestFakeTemplateErrors(t *testing.T) {
-	f := shipped(t)
-	for _, c := range []struct {
-		input string
-		want  string
-	}{
-		{`{"x":"Q"}`, "missing string \"format\""},
-		{`"{x}"`, `no field "x"`},
-		{`"{digits(0)}"`, "must be positive"},
-		{`name: {/no.such.path}`, "no entry"},
-		{`name: {..nope}`, "write {/nope}"},
-		{`{"format":"x"}`, "is a string"},
-		{`{/misc.country} {/misc.country.alpha2}`, "renders a level"},
-		{`{"format":"{/misc.country.alpha2} {x}","x":"{/misc.country}"}`, "reads a path into"},
-	} {
-		_, err := f.FakeTemplate(c.input)
-		if err == nil || !strings.Contains(err.Error(), c.want) {
-			t.Errorf("FakeTemplate(%q) = %v, want an error containing %q", c.input, err, c.want)
-		}
-	}
-}
-
-func TestFakeTemplateJSONString(t *testing.T) {
-	f := shipped(t)
-	got := tmpl(t, f, `"name: {/sv_SE.person.last}"`)
-	if !strings.HasPrefix(got, "name: ") || strings.Contains(got, "{") {
-		t.Fatalf("FakeTemplate(JSON string) = %q, want a rendered last name after the prefix", got)
-	}
-}
-
-func TestPaddedJSONIsRejected(t *testing.T) {
-	f := shipped(t)
-	in := `{"format":"{x}","x":["a","b"]}`
-	_, err := f.NewTemplate("  " + in + "  ")
-	if err == nil || !strings.Contains(err.Error(), "write "+in) {
-		t.Fatalf("NewTemplate(padded JSON) = %v, want an error naming the unpadded spelling", err)
-	}
-}
-
-func TestNewTemplateReusable(t *testing.T) {
-	f := shipped(t)
-	reusable, err := f.NewTemplate(`{digits(2)}`)
-	if err != nil {
-		t.Fatalf("NewTemplate: %v", err)
-	}
-	seen := map[string]bool{}
-	for i := 0; i < 50; i++ {
-		seen[reusable.Fake()] = true
-	}
-	if len(seen) < 2 {
-		t.Fatalf("Template.Fake() repeated %v, want varied draws from one compile", seen)
-	}
-}
-
-func TestFakeTemplateRepeatBound(t *testing.T) {
-	f := shipped(t)
-	_, err := f.FakeTemplate(`{"format":"{x}","repeat":200,"x":{"format":"{y}","repeat":200,"y":{"format":"z","repeat":200}}}`)
-	if err == nil || !strings.Contains(err.Error(), "maximum") {
-		t.Errorf("nested repeat over the cap = %v, want it rejected naming the maximum", err)
-	}
-}

loading_test.go

@@ -275,18 +275,6 @@ func TestNewErrors(t *testing.T) {
 			map[string]string{"a|b": `"1"`},
 			`category "a|b" contains "|"`,
 		},
-		"field name with a bracket": {
-			map[string]string{"a": `{"format":"{x}","x":"1","b[c":"2"}`},
-			`field "b[c" contains "["`,
-		},
-		"category name with a bracket": {
-			map[string]string{"[abc]": `"1"`},
-			`category "[abc]" contains "["`,
-		},
-		"field name with a quote": {
-			map[string]string{"a": `{"format":"{x}","x":"1","b\"c":"2"}`},
-			`field "b\"c" contains "\""`,
-		},
 		// An empty name is not a path segment, so List never offered it — while a
 		// bare {}, a trailing dot in Fake("a.") and a {/a.} reference all reached
 		// it. The engine accepted spellings it would never advertise.

node.go

@@ -57,15 +57,6 @@ type template struct {
 
 func (*template) isNode() {}
 
-// field is the node a path segment names; a binding is a render edge, not a field.
-func (t *template) field(seg string) (node, bool) {
-	if isRef(seg) {
-		return nil, false
-	}
-	n, ok := t.fields[seg]
-	return n, ok
-}
-
 // compile converts parsed JSON into a node tree, validating structure up front.
 // Only a choice's items carry a weight, so one here would be inert whatever its type.
 func compile(v any) (node, error) {
@@ -87,24 +78,10 @@ func compileItem(v any) (node, error) {
 	case map[string]any:
 		return compileTemplate(v)
 	default:
-		return nil, fmt.Errorf("a template value must be a string, a list or an object, not %s", jsonKind(v))
+		return nil, fmt.Errorf("unsupported node type %T", v)
 	}
 }
 
-// jsonKind names a JSON value a template cannot hold, in the data format's own
-// terms rather than the decoding library's.
-func jsonKind(v any) string {
-	switch v.(type) {
-	case float64:
-		return "a number"
-	case bool:
-		return "a boolean"
-	case nil:
-		return "null"
-	}
-	return fmt.Sprintf("%T", v)
-}
-
 func compileString(s string) (node, error) {
 	if err := checkTokens(s, nil); err != nil {
 		return nil, err
@@ -252,9 +229,6 @@ func readOptions(m map[string]any) (templateOptions, error) {
 		if repeat == 1 {
 			return o, fmt.Errorf("separator joins repeated renders, so it has no effect without a repeat above 1")
 		}
-		if o.separator == "" {
-			return o, fmt.Errorf("separator \"\" is the default, so it has no effect; drop it")
-		}
 	}
 	_, o.weighted = m["weight"]
 	return o, nil
@@ -302,8 +276,8 @@ func repeatOf(m map[string]any) (int, error) {
 	if r == 1 {
 		return 0, fmt.Errorf("repeat 1 is the default, so it has no effect; drop it")
 	}
-	if r > MaxRepeat { // caps the renders one repeat asks for; repeatCheck bounds what nested ones multiply to
-		return 0, fmt.Errorf("repeat %v exceeds the maximum %d", rv, MaxRepeat)
+	if r > maxLen { // cap so a fat-fingered repeat can't build a multi-GB string
+		return 0, fmt.Errorf("repeat %v exceeds the maximum %d", rv, maxLen)
 	}
 	return int(r), nil
 }
@@ -337,23 +311,23 @@ func weightOf(raw any) (float64, error) {
 
 // reservedInName is what a category, folder or field name may not contain: a dot
 // separates the segments of a path, '|' the arms of a token, '(' opens a function
-// call, braces delimit the token, '/' starts a reference, and brackets and a quote
-// open a JSON value. A name carrying one is rejected where it is authored rather
-// than where it would be unreachable.
-const reservedInName = ".|({}/[]\""
+// call, braces delimit the token and '/' starts a reference. A name carrying one is
+// reachable by no format, so it is rejected where it is authored rather than at
+// the token that cannot reach it.
+const reservedInName = ".|({}/"
 
 // reservedList spells reservedInName for an error message, so the two cannot drift.
 var reservedList = strings.Join(strings.Split(reservedInName, ""), " ")
 
-// checkName rejects a name the dot path, {token} and JSON grammars cannot spell.
-// Both a category or folder and a field go through it, so there is one answer to
-// what a name may contain.
+// checkName rejects a name the dot path and {token} grammars cannot spell. Both a
+// category or folder and a field go through it, so there is one answer to what a
+// name may contain.
 func checkName(name string) error {
 	if name == "" {
 		return fmt.Errorf("%q is empty, which is not a path segment, so List never offers it", name)
 	}
 	if i := strings.IndexAny(name, reservedInName); i >= 0 {
-		return fmt.Errorf("%q contains %q; a name may not use %s, which the dot path, {token} and JSON grammars reserve",
+		return fmt.Errorf("%q contains %q; a name may not use %s, which the dot path and {token} grammars reserve",
 			name, name[i:i+1], reservedList)
 	}
 	return nil

one_spelling_test.go

@@ -30,12 +30,11 @@ func TestRepeatedChoiceItemIsRejected(t *testing.T) {
 
 func TestInertObjectIsRejected(t *testing.T) {
 	for src, want := range map[string]string{
-		`{"format":"Malmö"}`:                                 `write "Malmö"`,
-		`{"format":"{digits(3)}"}`:                           `write "{digits(3)}"`,
-		`[{"format":"a","weight":1},"b"]`:                    "weight 1",
-		`{"format":"{x}","x":"v","repeat":1}`:                "repeat 1",
-		`{"format":"{x}","x":"v","separator":","}`:           "separator",
-		`{"format":"{x}","x":"v","repeat":2,"separator":""}`: "default",
+		`{"format":"Malmö"}`:                       `write "Malmö"`,
+		`{"format":"{digits(3)}"}`:                 `write "{digits(3)}"`,
+		`[{"format":"a","weight":1},"b"]`:          "weight 1",
+		`{"format":"{x}","x":"v","repeat":1}`:      "repeat 1",
+		`{"format":"{x}","x":"v","separator":","}`: "separator",
 	} {
 		if _, err := compile(parse(t, src)); err == nil || !strings.Contains(err.Error(), want) {
 			t.Errorf("compile(%s) = %v, want an error mentioning %s", src, err, want)
@@ -47,13 +46,3 @@ func TestInertObjectIsRejected(t *testing.T) {
 		}
 	}
 }
-
-func TestInlineFolderSigilsAreRejected(t *testing.T) {
-	f := shipped(t)
-	for _, input := range []string{"{.sv_SE.person.last}", "{..sv_SE.person.last}"} {
-		_, err := f.NewTemplate(input)
-		if err == nil || !strings.Contains(err.Error(), "write {/sv_SE.person.last}") {
-			t.Errorf("NewTemplate(%q) = %v, want an error naming the root spelling", input, err)
-		}
-	}
-}

path.go

@@ -40,7 +40,7 @@ func walkPath(n node, tail []string, w pathWalk) error {
 				return err
 			}
 		}
-		child, ok := n.field(tail[0])
+		child, ok := n.fields[tail[0]]
 		if !ok {
 			return fmt.Errorf("no field %q", tail[0])
 		}

path_test.go

@@ -136,17 +136,3 @@ func TestMissingFieldNamesItself(t *testing.T) {
 		t.Errorf("Fake(person.typo) = %v, want it to name the missing field", err)
 	}
 }
-
-func TestBindingKeyIsNotAPathSegment(t *testing.T) {
-	dir := writeData(t, map[string]string{
-		"color": `["red","blue"]`,
-		"name":  `{"format":"{/color} {w}","w":"x"}`,
-	})
-	f := newGenerator(t, dir, WithSeed(1))
-	if slices.Contains(f.List(), "name./color") {
-		t.Error("List() advertises a binding key")
-	}
-	if _, err := f.Fake("name./color"); err == nil || !strings.Contains(err.Error(), `no field "/color"`) {
-		t.Errorf("Fake(name./color) = %v, want a no-field error", err)
-	}
-}

perf_test.go

@@ -1,61 +0,0 @@
-package fejkdata
-
-import (
-	"fmt"
-	"strings"
-	"testing"
-	"testing/fstest"
-)
-
-// One Fake call descends depth levels: each level's "a" is the next template down.
-func nestedJSON(depth int) string {
-	s := `"leaf"`
-	for i := 0; i < depth; i++ {
-		s = fmt.Sprintf(`{"format":"{a}","a":%s}`, s)
-	}
-	return s
-}
-
-// One Fake call expands n sibling tokens.
-func wideTokenJSON(n int) string {
-	var toks, fields strings.Builder
-	for i := 0; i < n; i++ {
-		fmt.Fprintf(&toks, "{f%d}", i)
-		if i > 0 {
-			fields.WriteByte(',')
-		}
-		fmt.Fprintf(&fields, `"f%d":"x"`, i)
-	}
-	return fmt.Sprintf(`{"format":"%s",%s}`, toks.String(), fields.String())
-}
-
-func TestNoRenderAllocRegression(t *testing.T) {
-	shapes := []struct {
-		name string
-		json string
-		base float64
-	}{
-		{"nested depth 25", nestedJSON(25), 27},
-		{"nested depth 100", nestedJSON(100), 102},
-		{"wide 500 tokens", wideTokenJSON(500), 9},
-	}
-	for _, s := range shapes {
-		f, err := New(WithoutShippedData(), WithDataFS(fstest.MapFS{"x.json": {Data: []byte(s.json)}}))
-		if err != nil {
-			t.Fatalf("New(%s): %v", s.name, err)
-		}
-		allocs := testing.AllocsPerRun(10000, func() { f.Fake("x") })
-		if allocs > s.base*1.10 {
-			t.Errorf("%s: %.1f allocs/op regressed past %.1f (baseline %.1f + 10%%); bump the baseline only as a deliberate change", s.name, allocs, s.base*1.10, s.base)
-		}
-	}
-}
-
-func BenchmarkNestedDepth25(b *testing.B)  { benchPath(b, tmpData(b, "deep", nestedJSON(25)), "deep") }
-func BenchmarkNestedDepth100(b *testing.B) { benchPath(b, tmpData(b, "deep", nestedJSON(100)), "deep") }
-func BenchmarkWideTokens100(b *testing.B) {
-	benchPath(b, tmpData(b, "wide", wideTokenJSON(100)), "wide")
-}
-func BenchmarkWideTokens500(b *testing.B) {
-	benchPath(b, tmpData(b, "wide", wideTokenJSON(500)), "wide")
-}

reference.go

@@ -72,42 +72,35 @@ func refSegments(name string, folder []string) ([]string, error) {
 // error, never a random render-time one.
 func linkRefs(root map[string]node) error {
 	return eachTemplate(root, func(folder []string, path string, t *template) error {
-		return linkTemplateRefs(folder, path, t, root)
-	})
-}
-
-// linkTemplateRefs binds one template's references against root. A template with
-// none is left untouched, so an inline format that references nothing costs only
-// the refTokens scan.
-func linkTemplateRefs(folder []string, path string, t *template, root map[string]node) error {
-	names := refTokens(t.format)
-	if len(names) == 0 {
+		names := refTokens(t.format)
+		if len(names) == 0 {
+			return nil
+		}
+		if t.fields == nil {
+			t.fields = map[string]node{}
+		}
+		t.refs = make(map[string]refBinding, len(names))
+		for _, name := range names {
+			segments, err := refSegments(name, folder)
+			if err != nil {
+				return fmt.Errorf("%s: reference {%s}: %w", path, name, err)
+			}
+			head, target, tail, err := resolveRef(root, segments)
+			if err != nil {
+				return fmt.Errorf("%s: reference {%s}: %w", path, name, err)
+			}
+			key := "/" + strings.Join(head, ".")
+			if err := checkPath(target, tail, key); err != nil {
+				return fmt.Errorf("%s: reference {%s}: %w", path, name, err)
+			}
+			t.fields[key] = target
+			t.refs[name] = refBinding{key, tail}
+		}
+		if err := t.compileFormat(); err != nil {
+			return fmt.Errorf("%s: %w", path, err)
+		}
 		return nil
-	}
-	if t.fields == nil {
-		t.fields = map[string]node{}
-	}
-	t.refs = make(map[string]refBinding, len(names))
-	for _, name := range names {
-		segments, err := refSegments(name, folder)
-		if err != nil {
-			return fmt.Errorf("%s: reference {%s}: %w", path, name, err)
-		}
-		head, target, tail, err := resolveRef(root, segments)
-		if err != nil {
-			return fmt.Errorf("%s: reference {%s}: %w", path, name, err)
-		}
-		key := "/" + strings.Join(head, ".")
-		if err := checkPath(target, tail, key); err != nil {
-			return fmt.Errorf("%s: reference {%s}: %w", path, name, err)
-		}
-		t.fields[key] = target
-		t.refs[name] = refBinding{key, tail}
-	}
-	if err := t.compileFormat(); err != nil {
-		return fmt.Errorf("%s: %w", path, err)
-	}
-	return nil
+	})
 }
 
 // eachTemplate calls fn once per template, with the folder its category sits in

shipped_data_test.go

@@ -108,12 +108,6 @@ func TestFakeIsSafeForConcurrentUse(t *testing.T) {
 					return
 				}
 				f.List()
-				tmpl, err := f.NewTemplate("{/sv_SE.person.last}")
-				if err != nil {
-					t.Error(err)
-					return
-				}
-				tmpl.Fake()
 			}
 		}()
 	}

template.go

@@ -140,7 +140,7 @@ func checkTokens(format string, fields map[string]node) error {
 				}
 				continue // its target is checked at New (see linkRefs)
 			}
-			if err := checkArm(name, fields, len(names) == 1); err != nil {
+			if err := checkArm(name, fields); err != nil {
 				return fmt.Errorf("token {%s}: %w", t.body, err)
 			}
 		}
@@ -151,9 +151,7 @@ func checkTokens(format string, fields map[string]node) error {
 }
 
 // checkArm validates one sibling name or path against a template's fields.
-// wholeToken says the name is the token's entire body, so {/name} would render
-// the same value and can be offered as the reference spelling.
-func checkArm(name string, fields map[string]node, wholeToken bool) error {
+func checkArm(name string, fields map[string]node) error {
 	a := splitArm(name, nil)
 	if err := checkSegments(a); err != nil {
 		return err
@@ -166,13 +164,6 @@ func checkArm(name string, fields map[string]node, wholeToken bool) error {
 		if isOption(a.key) {
 			return fmt.Errorf("%q is an option and can never be a field", a.key)
 		}
-		if len(fields) == 0 {
-			hint := ""
-			if wholeToken && hintableRef(name) {
-				hint = fmt.Sprintf(" — write {/%s} to reference the data", name)
-			}
-			return fmt.Errorf("no field %q; a token names a sibling field, and this template has none%s", a.key, hint)
-		}
 		return fmt.Errorf("no field %q", a.key)
 	}
 	if err := checkPath(head, a.tail, a.key); err != nil {
@@ -181,17 +172,6 @@ func checkArm(name string, fields map[string]node, wholeToken bool) error {
 	return nil
 }
 
-// hintableRef reports whether {/name} is a reference the grammar accepts, so the
-// hint never names a spelling that fails too.
-func hintableRef(name string) bool {
-	for _, seg := range strings.Split(name, ".") {
-		if checkName(seg) != nil {
-			return false
-		}
-	}
-	return true
-}
-
 // tokenOperands lists the fields one {token} body reads as operands, empty for a
 // field token or a builtin that reads none.
 func tokenOperands(body string) []string {

template_test.go

@@ -8,13 +8,7 @@ import (
 )
 
 // engine builds a seeded generator with no loaded categories, for rendering tests.
-func engine(seed uint64) *Generator {
-	s, err := newRand(seed, true)
-	if err != nil {
-		panic(err)
-	}
-	return &Generator{rand: s}
-}
+func engine(seed uint64) *Generator { return &Generator{rand: newRand(seed, true)} }
 
 // parse unmarshals a JSON template fragment into its dynamic form.
 func parse(t *testing.T, s string) any {
@@ -233,29 +227,17 @@ func TestCompileErrors(t *testing.T) {
 		`{"format":"x","repeat":1.5}`,                                   // non-integer repeat
 		`{"format":"x","repeat":"two"}`,                                 // non-numeric repeat
 		`{"format":"x","repeat":2,"separator":5}`,                       // non-string separator
-		`"{nope()}"`,           // unknown function
-		`"{luhn(x)}"`,          // function given args it takes none of
-		`"{luhn(}"`,            // malformed function token
-		`"{int(1)}"`,           // wrong arity
-		`"{int(a,b)}"`,         // non-integer args
-		`"{int(5,1)}"`,         // min > max
-		`"{hex(0)}"`,           // count must be positive
-		`"{nanoid(-1)}"`,       // negative count
-		`"{base64(0)}"`,        // count must be positive
-		`"{float(1,2)}"`,       // wrong arity
-		`"{float(1,2,-1)}"`,    // negative decimals
-		`"{float(NaN,NaN,2)}"`, // bounds must be finite
-		`"{float(Inf,Inf,2)}"`, // same-sign infinities
-		`"{float(1,NaN,2)}"`,   // one NaN bound
-		`"{float(-Inf,1,2)}"`,  // one infinite bound
-		`"{digits(+5)}"`,       // a count is a plain integer
-		`"{digits(05)}"`,       // no leading zero
-		`"{int(+1,5)}"`,        // a bound is a plain integer
-		`"{int(5,5)}"`,         // a constant is written as text
-		`"{float(1,1,2)}"`,     // a constant is written as text
-		`{"format":"{x}","x":"v","repeat":2,"separator":""}`, // separator "" is the default
-		`"{calc(1/0)}"`, // a constant zero divisor
-		`{"format":"{calc(x/y)}","x":"1","y":"0"}`, // a fixed zero divisor
+		`"{nope()}"`,        // unknown function
+		`"{luhn(x)}"`,       // function given args it takes none of
+		`"{luhn(}"`,         // malformed function token
+		`"{int(1)}"`,        // wrong arity
+		`"{int(a,b)}"`,      // non-integer args
+		`"{int(5,1)}"`,      // min > max
+		`"{hex(0)}"`,        // count must be positive
+		`"{nanoid(-1)}"`,    // negative count
+		`"{base64(0)}"`,     // count must be positive
+		`"{float(1,2)}"`,    // wrong arity
+		`"{float(1,2,-1)}"`, // negative decimals
 		`"{iban(US)}"`,      // unsupported country
 		`"{seq(a,b)}"`,      // seq takes at most one name
 		`"{calc()}"`,        // calc needs an expression
@@ -365,17 +347,3 @@ func TestAlternationThreeWay(t *testing.T) {
 		t.Fatalf("3-way alternation produced %v, want A, B and C", seen)
 	}
 }
-
-func TestArgErrorsNameTheSpelling(t *testing.T) {
-	for src, want := range map[string]string{
-		`"{float(1,2,02)}"`:                 "write 2",
-		`{"format":"{calc(a,02)}","a":"1"}`: "write 2",
-		`"{digits(+5)}"`:                    "write 5",
-		`"{hex(99999999999999999999)}"`:     "exceeds the maximum",
-		`"{int(007,9)}"`:                    "write 7",
-	} {
-		if _, err := compile(parse(t, src)); err == nil || !strings.Contains(err.Error(), want) {
-			t.Errorf("compile(%s) = %v, want an error saying %q", src, err, want)
-		}
-	}
-}

todo.md

@@ -1,28 +0,0 @@
-# Release checklist
-
-What to settle before the first tag, then the work that follows in a later,
-data-heavy release.
-
-## Before the first release — settle the record flag and API contract
-
-- `--format` vocabulary — confirm `text`, `json`, `ndjson`, `csv`, `sql`; the
-  `json`-as-array vs `ndjson`-as-lines split; `--table` (the SQL INSERT target);
-  the `--separator` rejection on record formats; and the exit codes (misuse 2,
-  runtime 1).
-- Library surface — confirm `Record`, `FakeRecord`, `NewRecordTemplate`,
-  `RecordTemplate`, `Column`/`Columns()`, and the `JSON()`, `CSVHeader()`,
-  `CSVLine()`, `SQLInsert()` serializers.
-- Typed scalars — columns are strings today (`"42"`, quoted SQL). Confirm that
-  stays out of scope, or add a per-column `kind` before the tag.
-- Struct-filling — `fake:"..."` tags (reflection over an arbitrary struct) stay
-  out of scope; `Columns()` hands the caller the values to map themselves.
-  Confirm.
-- Independent reference draw — within one record every tailed reference to a
-  category is one draw, with no spelling for "these columns should disagree".
-  Confirm the per-record contract, or add the spelling.
-
-## Later, in a data-heavy release
-
-- Shipped-data de-duplication — `email.json`'s `local` is a drifted copy of
-  `username.json`; fold it in when the shipped set grows and we add lots more
-  data.

transform_test.go

@@ -51,9 +51,3 @@ func TestTransformArgs(t *testing.T) {
 		}
 	}
 }
-
-func TestAsciiKeepsDEL(t *testing.T) {
-	if got := mustRender(t, engine(1), `{"format":"{ascii(x)}","x":"a\u007fb"}`); got != "a\u007fb" {
-		t.Errorf("ascii over DEL = %q, want it kept: DEL is ASCII", got)
-	}
-}