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Hold a reference path like a sibling path; add the lowercase, uppercase and ascii transforms

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Lilleman auf Larv
2026-09-02 12:52:19 +02:00
parent 8fa33694b9
commit 31c2f12098
8 changed files with 372 additions and 174 deletions
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README.md
+10 -6
View File
@@ -273,10 +273,11 @@ reproducible. A time-based id (UUID v7, ULID) therefore draws its timestamp from
the rng, not the clock — the result is a valid, reproducible value, not a real
point in time.
There are four kinds. **Derivations** read the digits emitted so far, so put them
There are five kinds. **Derivations** read the digits emitted so far, so put them
after their payload; **samples** read only the rng, so they stand alone; one
**session counter** (`seq`) advances state held on the generator; and one
**computation** (`calc`) evaluates arithmetic over sibling fields. Arguments are
**session counter** (`seq`) advances state held on the generator; one
**computation** (`calc`) evaluates arithmetic over sibling fields; and the
**transforms** rewrite one field's value. Arguments are
validated at `New` (a bad count, range, country, or expression fails fast); a
length, count or decimal place beyond a sane maximum is rejected there too, so a
fat-fingered `hex(2000000000)` can't try to allocate gigabytes at render.
@@ -299,6 +300,7 @@ fat-fingered `hex(2000000000)` can't try to allocate gigabytes at render.
| `{iban(CC)}` | sample | a length- and mod-97-valid IBAN for country `CC` (BE, DE, DK, ES, FI, NO, SE) |
| `{seq()}`, `{seq(name)}` | session counter | next integer (from 1) in this generator's sequence; `name` selects an independent counter |
| `{calc(expr)}`, `{calc(expr,dp)}` | computation | value of an arithmetic expression over number literals and sibling fields; `dp` rounds |
| `{lowercase(x)}`, `{uppercase(x)}`, `{ascii(x)}` | transform | the field `x` — a name, a path or a `..path` — lower-cased, upper-cased, or folded to ASCII (`Åsa` → `Asa`); they nest: `{lowercase(ascii(x))}` |
`{ean()}` is also the ISBN-13 check (an ISBN-13 *is* an EAN-13 — build the 978/979
prefix in data and call `{ean()}`). `{iban()}` is a sample, not a derivation:
@@ -339,9 +341,11 @@ data dirs:
{ "format": "Hej, {..en_US.person}!" }
```
renders e.g. `Hej, Pat Smith!`. References are bound when you create the generator, so
a path that is unknown, names a folder, or steps through a choice
fails at `New`. A reference that leads back to its own value (directly, mutually,
renders e.g. `Hej, Pat Smith!`. A reference path is held like a sibling path:
`{..person.first} {..person.last}` read one person, and `{lowercase(..person.first)}`
reads that same draw, while a bare `{..die} {..die}` is two draws. References are
bound when you create the generator, so a path that is unknown, names a folder,
or reads a field not every variant of a choice carries fails at `New`. A reference that leads back to its own value (directly, mutually,
or through a chain) is a cycle that would never finish rendering, so it too is
rejected at `New`.
builtins.go
+97 -3
View File
@@ -6,6 +6,7 @@ import (
"math"
"strconv"
"strings"
"unicode"
)
// maxLen caps sample output lengths (hex, nanoid, base64) and maxDecimals caps
@@ -51,9 +52,10 @@ var builtins = map[string]builtin{
cc := a[0]
return func(s *session, _ string, _ []string) string { return iban(s, cc) }
}},
// calc is the one builtin that names operands (expand reads them for it);
// every other ignores them. 1 or 2 args: the expression and an optional decimals.
"calc": {arity: -1, check: checkCalc, prep: calcPrep},
"calc": {arity: -1, check: checkCalc, prep: calcPrep, operands: calcOperands},
"lowercase": {arity: 1, check: transformArg, prep: transformPrep(strings.ToLower), operands: transformOperand},
"uppercase": {arity: 1, check: transformArg, prep: transformPrep(strings.ToUpper), operands: transformOperand},
"ascii": {arity: 1, check: transformArg, prep: transformPrep(asciiFold), operands: transformOperand},
// seq is the one stateful builtin: a per-session counter from 1, advancing on
// each call. An optional name selects an independent counter; no name uses the
// default one. Deterministic by construction, so seeded output stays stable.
@@ -92,6 +94,98 @@ func chars(alphabet string) func([]string) callFn {
const hexDigits = "0123456789abcdef"
// transforms are the builtins that rewrite one operand's value; they nest, so
// {lowercase(ascii(x))} folds then lowers.
var transforms = map[string]func(string) string{
"ascii": asciiFold,
"lowercase": strings.ToLower,
"uppercase": strings.ToUpper,
}
// unwrapTransform peels nested transform calls off an operand arg, returning the
// field it finally names and the transforms to apply, innermost last.
func unwrapTransform(arg string) (leaf string, chain []func(string) string, err error) {
for {
name, args, isCall := funcCall(arg)
if !isCall {
return arg, chain, nil
}
fn, isTransform := transforms[name]
if !isTransform {
return "", nil, fmt.Errorf("%s(%s) is not a transform, so it cannot be an operand", name, strings.Join(args, ","))
}
if len(args) != 1 {
return "", nil, fmt.Errorf("%s takes 1 arg, got %d", name, len(args))
}
chain = append(chain, fn)
arg = args[0]
}
}
func transformArg(fields map[string]node, a []string) error {
leaf, _, err := unwrapTransform(a[0])
if err != nil {
return err
}
if isRef(leaf) {
if leaf == refPrefix {
return fmt.Errorf("reference has no path")
}
return nil
}
return checkArm(leaf, fields)
}
func transformOperand(a []string) []string {
leaf, _, err := unwrapTransform(a[0])
if err != nil {
return nil
}
return []string{leaf}
}
func transformPrep(outer func(string) string) func([]string) callFn {
return func(a []string) callFn {
_, chain, err := unwrapTransform(a[0])
if err != nil {
panic(fmt.Sprintf("fejkdata: transform arg %q reached prep unvalidated: %v", a[0], err))
}
return func(_ *session, _ string, operands []string) string {
v := operands[0]
for i := len(chain) - 1; i >= 0; i-- {
v = chain[i](v)
}
return outer(v)
}
}
}
// asciiFolds maps the Latin letters with diacritics or ligatures to ASCII.
var asciiFolds = map[rune]string{
'À': "A", 'Á': "A", 'Â': "A", 'Ã': "A", 'Ä': "A", 'Å': "A", 'Æ': "AE", 'Ç': "C",
'È': "E", 'É': "E", 'Ê': "E", 'Ë': "E", 'Ì': "I", 'Í': "I", 'Î': "I", 'Ï': "I",
'Ð': "D", 'Ñ': "N", 'Ò': "O", 'Ó': "O", 'Ô': "O", 'Õ': "O", 'Ö': "O", 'Ø': "O",
'Ù': "U", 'Ú': "U", 'Û': "U", 'Ü': "U", 'Ý': "Y", 'Þ': "Th", 'ß': "ss", 'Œ': "OE",
'à': "a", 'á': "a", 'â': "a", 'ã': "a", 'ä': "a", 'å': "a", 'æ': "ae", 'ç': "c",
'è': "e", 'é': "e", 'ê': "e", 'ë': "e", 'ì': "i", 'í': "i", 'î': "i", 'ï': "i",
'ð': "d", 'ñ': "n", 'ò': "o", 'ó': "o", 'ô': "o", 'õ': "o", 'ö': "o", 'ø': "o",
'ù': "u", 'ú': "u", 'û': "u", 'ü': "u", 'ý': "y", 'þ': "th", 'ÿ': "y", 'œ': "oe",
}
// asciiFold rewrites s to ASCII: folded Latin letters stay, any other non-ASCII
// rune is dropped.
func asciiFold(s string) string {
var b strings.Builder
for _, r := range s {
if r < unicode.MaxASCII {
b.WriteRune(r)
} else {
b.WriteString(asciiFolds[r])
}
}
return b.String()
}
// atoi parses an arg a builtin's check already validated. It panics rather than
// returning zero, so a check that stops covering its own args is a stack trace and
// not a silently wrong length, range or decimal count.
calc.go
+4 -20
View File
@@ -122,26 +122,10 @@ func indexVars(n calcNode, at map[string]int) calcNode {
return n
}
// calcOperands lists the sibling-field names every {calc(...)} token in a format
// reads, so cycle detection sees the field edges calc renders through (a function
// token otherwise carries no field edge).
func calcOperands(format string) []string {
var names []string
_ = eachToken(format, func(t ftoken) error {
if t.kind == 'b' {
names = append(names, calcTokenOperands(t.body)...)
}
return nil
})
return names
}
// calcTokenOperands lists the sibling-field names one {token} body reads, empty
// for anything that is not a {calc(...)}. checkCalc reports an expression that does
// not parse, so one that does not simply names nothing here.
func calcTokenOperands(body string) []string {
name, args, ok := funcCall(body)
if !ok || name != "calc" || len(args) == 0 {
// calcOperands lists the sibling-field names a calc's args read. checkCalc reports
// an expression that does not parse, so one that does not simply names nothing.
func calcOperands(args []string) []string {
if len(args) == 0 {
return nil
}
expr, err := parseCalc(args[0])
node.go
+5 -4
View File
@@ -45,6 +45,7 @@ type template struct {
grow int // minimum output size, to size the render buffer
fixed bool // no op varies, so every render is lit
lit string // the whole output when fixed
refs map[string]string // each {..path} the format reads -> the head it is bound under
// bound maps each field the format addresses by dotted path to one path token
// reading it, which is the half of an overlap the fences name. nil when the
// format takes no path.
@@ -92,7 +93,7 @@ func compileString(s string) (node, error) {
// compileFormat compiles the format into ops once every field is in place.
func (t *template) compileFormat() {
t.ops, t.grow, t.bound, t.held = compileOps(t.format)
t.ops, t.grow, t.bound, t.held = compileOps(t.format, t.refs)
t.fixed = true
for _, o := range t.ops {
if o.kind != 'l' {
@@ -214,15 +215,15 @@ func compileTemplate(m map[string]any) (node, error) {
return nil, err
}
t.compileFormat()
if err := checkNoOverlap(format, t.bound); err != nil {
if err := checkNoOverlap(format, t.bound, nil); err != nil {
return nil, err
}
return t, nil
}
// checkPath reports whether a token's dotted tail can address a node whichever way
// the draw goes, by the reachability rule descend applies — a multi-variant choice
// must carry the whole remaining path in the set every variant shares — plus the
// the draw goes, by the reachability rule descend applies — a choice must carry
// the whole remaining path in the set every variant shares — plus the
// rules a held draw adds, which descend has no need of: a level a path reads may
// not carry a repeat, and each variant answers for that itself. So a path that
// validates here resolves on every render, and a typo is a New-time error.
reference.go
+139 -74
View File
@@ -8,33 +8,47 @@ import (
// refPrefix marks a {..path} token: a reference to a node elsewhere in the data
// root rather than a sibling field. The path is resolved across every loaded
// directory (see linkRefs), and is stricter than the one Fake takes: a reference
// binds one node, so it cannot step through a choice even where Fake and List can.
// directory (see linkRefs).
const refPrefix = ".."
func isRef(name string) bool { return strings.HasPrefix(name, refPrefix) }
// linkRefs resolves every {..path} reference in the assembled tree, binding the
// target node into the referring template's fields under the token's key so the
// ordinary resolver renders it like a sibling. It runs once, after all data is
// merged, so a reference sees the final (override-resolved) tree. A path that is
// unknown, names a folder, or steps through a multi-variant choice fails here,
// keeping a bad reference a New-time error, never a random render-time one.
// linkRefs resolves every {..path} reference in the assembled tree. The head of the
// path — up to the category it names — is bound into the referring template's
// fields, and the rest reads into it the way a sibling path does, so a reference
// is held like a sibling. It runs once, after all data is merged, so a reference
// sees the final (override-resolved) tree. A path that is unknown, names a folder,
// or reads a field not every variant carries fails here, keeping a bad reference a
// New-time error, never a random render-time one.
func linkRefs(root map[string]node) error {
return walkNodes(root, func(path string, n node) error {
t, ok := n.(*template)
if !ok {
return nil
}
for _, name := range refTokens(t.format) {
target, err := lookup(root, strings.Split(name[len(refPrefix):], "."))
if err != nil {
return fmt.Errorf("%s: reference {%s}: %w", path, name, err)
names := refTokens(t.format)
if len(names) == 0 {
return nil
}
if t.fields == nil {
t.fields = map[string]node{}
}
t.fields[name] = target
t.refs = make(map[string]string, len(names))
for _, name := range names {
head, target, tail, err := resolveRef(root, strings.Split(name[len(refPrefix):], "."))
if err != nil {
return fmt.Errorf("%s: reference {%s}: %w", path, name, err)
}
key := refPrefix + 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] = key
}
t.compileFormat()
if err := checkNoOverlap(t.format, t.bound, t.refs); err != nil {
return fmt.Errorf("%s: %w", path, err)
}
return nil
})
@@ -43,7 +57,7 @@ func linkRefs(root map[string]node) error {
// 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, a calc operand); this settles the rest — a reference, whether it
// 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.
//
// It runs after checkNoCycles, whose guarantee is what lets the walk terminate.
@@ -57,33 +71,48 @@ func checkBoundLevelsHeld(root map[string]node) error {
for head := range t.held {
heads = append(heads, head)
}
sort.Strings(heads) // so which overlap is reported does not vary
// Operand heads first, then paths, each in name order: a level read both
// ways is reported by the operand's fence, and which overlap is reported
// does not vary.
sort.Slice(heads, func(i, j int) bool {
_, pi := t.bound[heads[i]]
_, pj := t.bound[heads[j]]
if pi != pj {
return !pi
}
return heads[i] < heads[j]
})
readers := boundReaders(t.format, t.bound, t.refs)
for _, head := range heads {
// What one draw answers for depends on how the draw is read. A path may
// read into anything the level contains; a calc renders its operand, so
// that draw fixes exactly the value the render produces.
// What one draw answers for depends on how the draw is read: a path pins
// the levels it passes through and the leaf it lands on, an operand
// exactly the value its render produces.
held := map[node]bool{}
reader, isPath := t.bound[head]
if isPath {
cover(t.fields[head], held)
for _, r := range readers {
if a := splitArm(r.name, t.refs); a.key == head {
coverPath(t.fields[head], a.tail, held)
}
}
} else {
operandDraw(t.fields[head], held)
}
if len(held) == 0 {
continue // an early out: a literal head holds nothing to reach
continue // an early out: a fixed head holds nothing to reach
}
// One seen set across the edges: a node that cannot reach the level
// cannot reach it by another route either, so it is walked once here.
seen := map[node]bool{}
for _, e := range renderEdges(t) {
if splitArm(e.label).key == head {
if splitArm(e.label, t.refs).key == head {
continue // a token or operand reading this draw, the routes allowed
}
if renders(e.to, held, seen) {
if isPath {
return fmt.Errorf("%s: %s renders %q, which {%s} reads a path into; name the fields you want instead", path, e.reached(), head, reader)
}
return fmt.Errorf("%s: %s renders %q, which a {calc()} also reads; reach it one way so it is drawn once", path, e.reached(), head)
return fmt.Errorf("%s: %s renders %q, which a {%s()} also reads; reach it one way so it is drawn once", path, e.reached(), head, operandReader(t, head))
}
}
}
@@ -91,28 +120,63 @@ func checkBoundLevelsHeld(root map[string]node) error {
})
}
// cover collects what one held draw of a level answers for: the level and
// everything contained in it, since a path may read any of it. A fixed string is
// left out — it cannot disagree with itself.
func cover(n node, into map[node]bool) {
if isFixed(n) {
// operandReader names the builtin whose operand holds head.
func operandReader(t *template, head string) string {
fn := ""
_ = eachToken(t.format, func(tok ftoken) error {
if tok.kind != 'b' || fn != "" {
return nil
}
if name, _, isFunc := funcCall(tok.body); isFunc {
for _, operand := range tokenOperands(tok.body) {
if splitArm(operand, t.refs).key == head {
fn = name
}
}
}
return nil
})
return fn
}
// coverPath collects what holding one path pins: every choice level the path
// passes through, whole, and the leaf it renders.
func coverPath(n node, tail []string, into map[node]bool) {
if _, isChoice := n.(*choice); isChoice || len(tail) == 0 {
cover(n, into, false)
return
}
into[n] = true
for _, c := range contained(n) {
cover(c.node, into)
t, ok := n.(*template)
if !ok {
return
}
if child, ok := t.fields[tail[0]]; ok {
coverPath(child, tail[1:], into)
}
}
// operandDraw collects what one held draw of a {calc()} operand answers for: the
// operand and what rendering it settles inside itself. A calc renders its operand
// cover collects a level and everything contained in it. A fixed string outside a
// choice is left out — it cannot disagree with itself — but inside one each
// variant carries its own, so there it counts.
func cover(n node, into map[node]bool, inChoice bool) {
if isFixed(n) && !inChoice {
return
}
into[n] = true
_, isChoice := n.(*choice)
for _, c := range contained(n) {
cover(c.node, into, inChoice || isChoice)
}
}
// operandDraw collects what one held draw of an operand answers for: the operand
// and what rendering it settles inside itself. The builtin renders its operand
// whole, so that draw fixes every value the render produced, and a second route to
// any of them disagrees with it.
//
// The walk stops at a {..path} edge, which is where the operand's own value ends
// and a shared source begins: two names referencing one category are two draws, the
// same rule {word} {word} follows. cover stops there too, by way of named, so both
// halves of the fence end at the same boundary.
// same rule {word} {word} follows.
func operandDraw(n node, into map[node]bool) {
if isFixed(n) {
return
@@ -232,43 +296,35 @@ func sortedNames(m map[string]node) []string {
return names
}
// lookup finds the single node a reference path names, walking groups and
// template fields by segment. A missing segment, a folder target, or a step
// through a choice (which has no one value to bind) is an error.
func lookup(root map[string]node, segments []string) (node, error) {
// resolveRef walks a reference path through the folders to the category it names,
// returning that head, the node, and the tail left to read into it.
func resolveRef(root map[string]node, segments []string) (head []string, target node, tail []string, err error) {
var n node = &group{children: root}
for i := 0; i < len(segments); i++ {
switch c := n.(type) {
case *group:
child, ok := c.children[segments[i]]
i := 0
for ; i < len(segments); i++ {
g, ok := n.(*group)
if !ok {
return nil, fmt.Errorf("no entry %q", segments[i])
break
}
child, ok := g.children[segments[i]]
if !ok {
return nil, nil, nil, fmt.Errorf("no entry %q", segments[i])
}
n = child
case *template:
child, ok := c.fields[segments[i]]
if !ok {
return nil, fmt.Errorf("no field %q", segments[i])
}
n = child
case *choice:
return nil, fmt.Errorf("%q steps through a %d-way choice", segments[i], len(c.items))
default:
return nil, fmt.Errorf("cannot descend into %T at %q", n, segments[i])
}
}
if _, ok := n.(*group); ok {
return nil, fmt.Errorf("names a folder, not a value")
return nil, nil, nil, fmt.Errorf("names a folder, not a value")
}
return n, nil
return segments[:i], n, segments[i:], nil
}
// refTokens returns just the {..path} reference names among a format's field
// tokens (linkRefs binds each into the template's fields).
// refTokens returns the {..path} names a format reads, as tokens or as operands.
func refTokens(format string) []string {
var refs []string
for _, name := range fieldTokens(format) {
if isRef(name) {
seen := map[string]bool{}
for _, name := range append(fieldTokens(format), operandTokens(format)...) {
if isRef(name) && !seen[name] {
seen[name] = true
refs = append(refs, name)
}
}
@@ -276,27 +332,27 @@ func refTokens(format string) []string {
}
// renderEdge is a child a node renders into, labelled by what reaches it (a field
// name, reference, or choice index) for a readable cycle report. operand marks a
// label that is a {calc()} operand name rather than a token, so an error can name
// it the way the author wrote it.
// name, reference, or choice index) for a readable cycle report. operand names
// the builtin when the label is its operand rather than a token, so an error can
// name it the way the author wrote it.
type renderEdge struct {
to node
label string
operand bool
operand string
}
// reached names an edge as the author spelled it, the vocabulary boundReaders uses
// for the sibling fence.
func (e renderEdge) reached() string {
if e.operand {
return fmt.Sprintf("calc operand %q", e.label)
if e.operand != "" {
return fmt.Sprintf("%s operand %q", e.operand, e.label)
}
return "{" + e.label + "}"
}
// renderEdges lists the children rendering n recurses into, mirroring expand: a
// choice's items, and a template's field/reference tokens plus its calc operands.
// A group renders nothing, so it has no edges.
// choice's items, and a template's field/reference tokens plus its operands. A
// group renders nothing, so it has no edges.
func renderEdges(n node) []renderEdge {
switch n := n.(type) {
case *choice:
@@ -307,8 +363,8 @@ func renderEdges(n node) []renderEdge {
return es
case *template:
var es []renderEdge
add := func(name string, operand bool) {
a := splitArm(name)
add := func(name, operand string) {
a := splitArm(name, n.refs)
c, ok := n.fields[a.key]
if !ok {
return
@@ -317,12 +373,21 @@ func renderEdges(n node) []renderEdge {
es = append(es, renderEdge{leaf, name, operand})
}
}
for _, name := range fieldTokens(n.format) {
add(name, false)
_ = eachToken(n.format, func(t ftoken) error {
if t.kind != 'b' {
return nil
}
for _, name := range calcOperands(n.format) {
add(name, true)
if fn, _, isFunc := funcCall(t.body); isFunc {
for _, operand := range tokenOperands(t.body) {
add(operand, fn)
}
return nil
}
for _, name := range strings.Split(t.body, "|") {
add(name, "")
}
return nil
})
return es
default:
return nil
render.go
+2 -2
View File
@@ -143,8 +143,8 @@ func expand(s *session, t *template) string {
var operands []string
if len(o.operands) > 0 {
operands = make([]string, len(o.operands))
for j, name := range o.operands {
operands[j] = readField(s, t, held, arm{name: name, key: name})
for j, a := range o.operands {
operands[j] = readField(s, t, held, a)
}
}
b.WriteString(o.call(s, b.String(), operands)) // b.String() is the output so far
template.go
+104 -54
View File
@@ -69,6 +69,9 @@ type builtin struct {
// prep parses validated args once, at compile time, into the closure expand calls.
prep func(args []string) callFn
check func(fields map[string]node, args []string) error
// operands names the fields the call reads, which expand renders for it; nil
// for a builtin that reads none.
operands func(args []string) []string
}
// funcCall splits a "{token}" body shaped name(args) into its parts; ok is false
@@ -137,23 +140,9 @@ func checkTokens(format string, fields map[string]node) error {
}
continue // a root reference; its target is checked at New (see linkRefs)
}
a := splitArm(name)
if err := checkSegments(a); err != nil {
if err := checkArm(name, fields); err != nil {
return fmt.Errorf("token {%s}: %w", t.body, err)
}
head, ok := fields[a.key]
if !ok {
if a.key == "" {
return fmt.Errorf("token {%s}: a name is never empty, so this token can name no field", t.body)
}
if isOption(a.key) {
return fmt.Errorf("token {%s}: %q is an option and can never be a field", t.body, a.key)
}
return fmt.Errorf("token {%s}: no field %q", t.body, a.key)
}
if err := checkPath(head, a.tail, a.key); err != nil {
return fmt.Errorf("token {%s}: field %q: %w", t.body, a.key, err)
}
}
// Last, so an arm broken on its own terms is reported as that: a repeat is
// the consequence of such a mistake, not the mistake itself.
@@ -161,6 +150,54 @@ func checkTokens(format string, fields map[string]node) error {
})
}
// checkArm validates one sibling name or path against a template's fields.
func checkArm(name string, fields map[string]node) error {
a := splitArm(name, nil)
if err := checkSegments(a); err != nil {
return err
}
head, ok := fields[a.key]
if !ok {
if a.key == "" {
return fmt.Errorf("a name is never empty, so this token can name no field")
}
if isOption(a.key) {
return fmt.Errorf("%q is an option and can never be a field", a.key)
}
return fmt.Errorf("no field %q", a.key)
}
if err := checkPath(head, a.tail, a.key); err != nil {
return fmt.Errorf("field %q: %w", a.key, err)
}
return nil
}
// 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 {
name, args, ok := funcCall(body)
if !ok {
return nil
}
b, known := builtins[name]
if !known || b.operands == nil {
return nil
}
return b.operands(args)
}
// operandTokens lists every operand the builtins in a format read.
func operandTokens(format string) []string {
var names []string
_ = eachToken(format, func(t ftoken) error {
if t.kind == 'b' {
names = append(names, tokenOperands(t.body)...)
}
return nil
})
return names
}
// checkNoRepeatedArm rejects {a|a|b}: an alternation picks its arms evenly, so a
// repeated one is a second spelling of weight. The error names the spelling that
// does skew a pick.
@@ -192,10 +229,11 @@ func fieldTokens(format string) []string {
return names
}
// arm is one alternative of a {a|b} token, split into the key naming the node in
// a template's fields (a sibling field, or the whole "..path" string a reference is
// bound under) and the tail of a dotted path into it. A non-empty tail is what makes
// the arm a bound draw: its head is drawn once per expansion (see compileOps).
// arm is one alternative of a {a|b} token or one operand, split into the key
// naming the node in a template's fields (a sibling field, or the "..path" head a
// reference is bound under) and the tail of a dotted path into it. A non-empty
// tail is what makes the arm a bound draw: its head is drawn once per expansion
// (see compileOps).
type arm struct {
name string // as written, and the key a bound draw's value is held under
key string
@@ -203,22 +241,29 @@ type arm struct {
steps []string // key per level passed through; the head and leaf hold their own
}
// splitArm splits one token alternative into key and tail. A reference keeps its
// dots — linkRefs binds it whole — so only a sibling name reads as a path.
func splitArm(name string) arm {
// splitArm splits one name into key and tail. refs maps a reference to the head
// linkRefs bound it under; before linking, a reference is whole.
func splitArm(name string, refs map[string]string) arm {
if isRef(name) {
key, bound := refs[name]
if !bound || key == name {
return arm{name: name, key: name}
}
return pathArm(name, key, strings.Split(name[len(key)+1:], "."))
}
head, tail, dotted := strings.Cut(name, ".")
if !dotted {
return arm{name: name, key: name}
}
segs := strings.Split(tail, ".")
return pathArm(name, head, strings.Split(tail, "."))
}
func pathArm(name, key string, segs []string) arm {
var steps []string
for i := 0; i < len(segs)-1; i++ { // every level except the leaf's own
steps = append(steps, head+"."+strings.Join(segs[:i+1], "."))
steps = append(steps, key+"."+strings.Join(segs[:i+1], "."))
}
return arm{name: name, key: head, tail: segs, steps: steps}
return arm{name: name, key: key, tail: segs, steps: steps}
}
// checkNoOverlap rejects a format that both renders a level and reads a path into
@@ -226,8 +271,8 @@ func splitArm(name string) arm {
// level's held draw while rendering the level expands it afresh, so their values
// would disagree. Names are compared in sorted order, so which pair is reported
// does not depend on where the tokens sit.
func checkNoOverlap(format string, bound map[string]string) error {
names := boundReaders(format, bound)
func checkNoOverlap(format string, bound map[string]string, refs map[string]string) error {
names := boundReaders(format, bound, refs)
// Stable over one format-order scan, so two readers of one name (a token and a
// calc operand both naming "p") are reported as the format writes them.
sort.SliceStable(names, func(i, j int) bool { return names[i].name < names[j].name })
@@ -245,23 +290,24 @@ func checkNoOverlap(format string, bound map[string]string) error {
type reader struct{ name, label string }
// boundReaders lists every way a format reaches a bound field, in the order the
// format writes them. A calc operand renders its field, so it names a level exactly
// format writes them. An operand renders its field, so it names a level exactly
// as a token does; one scan finds both, which is what puts them in one order.
func boundReaders(format string, bound map[string]string) []reader {
func boundReaders(format string, bound map[string]string, refs map[string]string) []reader {
var names []reader
_ = eachToken(format, func(t ftoken) error {
if t.kind != 'b' {
return nil
}
if _, _, isFunc := funcCall(t.body); isFunc {
for _, operand := range calcTokenOperands(t.body) {
if _, isBound := bound[operand]; isBound {
names = append(names, reader{operand, fmt.Sprintf("calc operand %q", operand)})
if fn, _, isFunc := funcCall(t.body); isFunc {
for _, operand := range tokenOperands(t.body) {
a := splitArm(operand, refs)
if _, isBound := bound[a.key]; isBound {
names = append(names, reader{a.name, fmt.Sprintf("%s operand %q", fn, operand)})
}
}
return nil
}
for _, a := range splitArms(t.body) {
for _, a := range splitArms(t.body, refs) {
if _, isBound := bound[a.key]; isBound {
names = append(names, reader{a.name, "token {" + a.name + "}"})
}
@@ -290,11 +336,11 @@ func checkSegments(a arm) error {
}
// splitArms splits a token body's '|' alternatives.
func splitArms(body string) []arm {
func splitArms(body string, refs map[string]string) []arm {
parts := strings.Split(body, "|")
arms := make([]arm, len(parts))
for i, p := range parts {
arms[i] = splitArm(p)
arms[i] = splitArm(p, refs)
}
return arms
}
@@ -312,30 +358,38 @@ type op struct {
lit string // kind 'l'
arms []arm // kind 'f': the '|' alternatives, split into key and path once
call callFn
// operands names the sibling fields a {calc()} reads, in the order calcVars
// fixed; expand reads them before the call. nil for every other builtin.
operands []string
// operands are the fields the builtin reads, in the order its operands func
// fixed; expand reads them before the call. nil for a builtin that reads none.
operands []arm
}
// compileOps turns a format string into ops, and returns the size of its literal
// text to size the render buffer, plus two sets. bound is the levels the format
// addresses by dotted path, each mapped to the first path reading it, which is what
// the overlap fences name. held is every name drawn once per expansion — those
// levels, plus the siblings a {calc()} reads, so an operand shown is the operand
// levels, plus the fields an operand reads, so an operand shown is the operand
// computed. Both are nil when the format needs neither, so data that uses neither
// carries no render-time cost. Call checkTokens first: it is what proves the scan
// and every token are valid.
func compileOps(format string) ([]op, int, map[string]string, map[string]bool) {
func compileOps(format string, refs map[string]string) ([]op, int, map[string]string, map[string]bool) {
var ops []op
var lit strings.Builder
var bound map[string]string
var held map[string]bool
grow := 0
hold := func(name string) {
hold := func(a arm) {
if held == nil {
held = map[string]bool{}
}
held[name] = true
held[a.key] = true
if len(a.tail) > 0 {
if bound == nil {
bound = map[string]string{}
}
if _, named := bound[a.key]; !named {
bound[a.key] = a.name // the first path reading it, for error messages
}
}
}
flush := func() {
if lit.Len() > 0 {
@@ -351,22 +405,18 @@ func compileOps(format string) ([]op, int, map[string]string, map[string]bool) {
case 'b':
flush()
if name, args, ok := funcCall(t.body); ok {
operands := calcTokenOperands(t.body)
for _, operand := range operands {
hold(operand) // a calc renders its operand, so the expansion holds that draw
var operands []arm
for _, operand := range tokenOperands(t.body) {
a := splitArm(operand, refs)
hold(a) // the builtin renders its operand, so the expansion holds that draw
operands = append(operands, a)
}
ops = append(ops, op{kind: 'b', call: builtins[name].prep(args), operands: operands})
} else {
arms := splitArms(t.body)
arms := splitArms(t.body, refs)
for _, a := range arms {
if len(a.tail) > 0 {
if bound == nil {
bound = map[string]string{}
}
if _, named := bound[a.key]; !named {
bound[a.key] = a.name // the first path reading it, for error messages
}
hold(a.key)
hold(a)
}
}
ops = append(ops, op{kind: 'f', arms: arms})