385 lines
12 KiB
Go
385 lines
12 KiB
Go
package fejkdata
|
|
|
|
import (
|
|
"fmt"
|
|
"sort"
|
|
"strings"
|
|
)
|
|
|
|
// 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 multi-variant choice even where Fake
|
|
// and List can.
|
|
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.
|
|
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)
|
|
}
|
|
t.fields[name] = target
|
|
}
|
|
return nil
|
|
})
|
|
}
|
|
|
|
// 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
|
|
// sits in that format or in anything the format renders, however deep.
|
|
//
|
|
// 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
|
|
}
|
|
heads := make([]string, 0, len(t.held))
|
|
for head := range t.held {
|
|
heads = append(heads, head)
|
|
}
|
|
sort.Strings(heads) // so which overlap is reported does not vary
|
|
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.
|
|
held := map[node]bool{}
|
|
reader, isPath := t.bound[head]
|
|
if isPath {
|
|
cover(t.fields[head], held)
|
|
} else {
|
|
operandDraw(t.fields[head], held)
|
|
}
|
|
if len(held) == 0 {
|
|
continue // an early out: a literal 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 {
|
|
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 nil
|
|
})
|
|
}
|
|
|
|
// 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) {
|
|
return
|
|
}
|
|
into[n] = true
|
|
for _, c := range contained(n) {
|
|
cover(c.node, 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
|
|
// 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.
|
|
func operandDraw(n node, into map[node]bool) {
|
|
if isFixed(n) {
|
|
return
|
|
}
|
|
if into[n] {
|
|
return
|
|
}
|
|
into[n] = true
|
|
for _, e := range renderEdges(n) {
|
|
if isRef(e.label) {
|
|
continue
|
|
}
|
|
operandDraw(e.to, into)
|
|
}
|
|
}
|
|
|
|
// isFixed is a string that varies nothing: fixed text with no fields to read into.
|
|
func isFixed(n node) bool {
|
|
t, ok := n.(*template)
|
|
return ok && t.fixed && len(t.fields) == 0
|
|
}
|
|
|
|
// renders reports whether rendering n can reach anything in want, following the
|
|
// same edges expand does. seen keeps a node shared by several routes from being
|
|
// walked twice; checkNoCycles has already proved the graph is a DAG, so the walk
|
|
// ends.
|
|
func renders(n node, want, seen map[node]bool) bool {
|
|
if want[n] {
|
|
return true
|
|
}
|
|
if seen[n] {
|
|
return false
|
|
}
|
|
seen[n] = true
|
|
for _, e := range renderEdges(n) {
|
|
if renders(e.to, want, seen) {
|
|
return true
|
|
}
|
|
}
|
|
return false
|
|
}
|
|
|
|
// walkNodes calls fn once per contained node, passing the dot path that reaches it,
|
|
// 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 {
|
|
seen := map[node]bool{}
|
|
var visit func(string, node) error
|
|
visit = func(path string, n node) error {
|
|
if n == nil || seen[n] {
|
|
return nil
|
|
}
|
|
seen[n] = true
|
|
if err := fn(path, n); err != nil {
|
|
return err
|
|
}
|
|
for _, c := range contained(n) {
|
|
if err := visit(join(path, c.name), c.node); err != nil {
|
|
return err
|
|
}
|
|
}
|
|
return nil
|
|
}
|
|
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
|
|
// no segment, matching how a dot path steps over a choice.
|
|
type namedNode struct {
|
|
name string
|
|
node node
|
|
}
|
|
|
|
func contained(n node) []namedNode {
|
|
switch n := n.(type) {
|
|
case *group:
|
|
return named(n.children)
|
|
case *choice:
|
|
out := make([]namedNode, len(n.items))
|
|
for i, it := range n.items {
|
|
out[i] = namedNode{node: it}
|
|
}
|
|
return out
|
|
case *template:
|
|
return named(n.fields)
|
|
default:
|
|
return nil
|
|
}
|
|
}
|
|
|
|
// named skips a bound {..path} key: it is a render edge, not containment, so using
|
|
// it as a path segment would report a node under a path that does not reach it. Only
|
|
// a template's fields hold bindings — loadDir skips a dot-prefixed entry, so a
|
|
// group's children never carry the prefix — so this one skip serves both.
|
|
func named(m map[string]node) []namedNode {
|
|
out := make([]namedNode, 0, len(m))
|
|
for _, name := range sortedNames(m) {
|
|
if isRef(name) {
|
|
continue
|
|
}
|
|
out = append(out, namedNode{name: name, node: m[name]})
|
|
}
|
|
return out
|
|
}
|
|
|
|
func sortedNames(m map[string]node) []string {
|
|
names := make([]string, 0, len(m))
|
|
for name := range m {
|
|
names = append(names, name)
|
|
}
|
|
sort.Strings(names)
|
|
return names
|
|
}
|
|
|
|
// lookup finds the single node a reference path names, walking groups and
|
|
// template fields by segment and descending a single-variant choice as a
|
|
// transparent wrapper. A missing segment, a folder target, or a step through a
|
|
// multi-variant choice (which has no one value to bind) is an error.
|
|
func lookup(root map[string]node, segments []string) (node, 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]]
|
|
if !ok {
|
|
return 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:
|
|
if len(c.items) != 1 {
|
|
return nil, fmt.Errorf("%q steps through a %d-way choice", segments[i], len(c.items))
|
|
}
|
|
n, i = c.items[0], i-1 // a choice consumes no segment; reprocess it unwrapped
|
|
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 n, nil
|
|
}
|
|
|
|
// refTokens returns just the {..path} reference names among a format's field
|
|
// tokens (linkRefs binds each into the template's fields).
|
|
func refTokens(format string) []string {
|
|
var refs []string
|
|
for _, name := range fieldTokens(format) {
|
|
if isRef(name) {
|
|
refs = append(refs, name)
|
|
}
|
|
}
|
|
return refs
|
|
}
|
|
|
|
// 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.
|
|
type renderEdge struct {
|
|
to node
|
|
label string
|
|
operand bool
|
|
}
|
|
|
|
// 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)
|
|
}
|
|
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.
|
|
func renderEdges(n node) []renderEdge {
|
|
switch n := n.(type) {
|
|
case *choice:
|
|
es := make([]renderEdge, len(n.items))
|
|
for i, it := range n.items {
|
|
es[i] = renderEdge{to: it, label: fmt.Sprintf("[%d]", i)}
|
|
}
|
|
return es
|
|
case *template:
|
|
var es []renderEdge
|
|
add := func(name string, operand bool) {
|
|
a := splitArm(name)
|
|
c, ok := n.fields[a.key]
|
|
if !ok {
|
|
return
|
|
}
|
|
for _, leaf := range pathLeaves(c, a.tail) {
|
|
es = append(es, renderEdge{leaf, name, operand})
|
|
}
|
|
}
|
|
for _, name := range fieldTokens(n.format) {
|
|
add(name, false)
|
|
}
|
|
for _, name := range calcOperands(n.format) {
|
|
add(name, true)
|
|
}
|
|
return es
|
|
default:
|
|
return nil
|
|
}
|
|
}
|
|
|
|
// pathLeaves lists what a token's dotted tail renders. A path draws the levels it
|
|
// passes through but renders only what it lands on, so the leaf is the edge — a
|
|
// bare token, whose tail is empty, lands on the field itself. A choice on the way
|
|
// contributes every variant, since any of them may be the one drawn. checkPath has
|
|
// already proved the tail resolves in every variant, so the walk drops nothing.
|
|
func pathLeaves(n node, tail []string) []node {
|
|
if len(tail) == 0 {
|
|
return []node{n}
|
|
}
|
|
if c, ok := n.(*choice); ok {
|
|
var out []node
|
|
for _, it := range c.items {
|
|
out = append(out, pathLeaves(it, tail)...)
|
|
}
|
|
return out
|
|
}
|
|
return pathLeaves(child(n, tail[0]), tail[1:])
|
|
}
|
|
|
|
// checkNoCycles rejects a reference cycle: a node whose rendering can reach itself
|
|
// — directly, mutually, or through a chain — never terminates, so it must fail at
|
|
// New rather than stack-overflow at render. It is a depth-first walk of the render
|
|
// graph (renderEdges); grey marks nodes on the current path so a back-edge to one
|
|
// is the cycle, while black lets a shared node (a DAG, not a cycle) be skipped.
|
|
// Every node is a root: a field its parent's format never renders is still reachable
|
|
// by dot path, so a cycle in one would otherwise reach render and be fatal there.
|
|
func checkNoCycles(root map[string]node) error {
|
|
const (
|
|
grey = 1
|
|
black = 2
|
|
)
|
|
color := map[node]int{}
|
|
var visit func(n node, path string) error
|
|
visit = func(n node, path string) error {
|
|
switch color[n] {
|
|
case grey:
|
|
return fmt.Errorf("reference cycle: %s", path)
|
|
case black:
|
|
return nil
|
|
}
|
|
color[n] = grey
|
|
for _, e := range renderEdges(n) {
|
|
if err := visit(e.to, path+" -> "+e.label); err != nil {
|
|
return err
|
|
}
|
|
}
|
|
color[n] = black
|
|
return nil
|
|
}
|
|
return walkNodes(root, func(path string, n node) error { return visit(n, path) })
|
|
}
|