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44x 44x 44x 546x | /**
* @file build.js
* @description Builds the template IR from template source.
*
* This runs on the template as the developer wrote it -- after declarations and
* imports are removed and scoped-CSS classes are applied, but *before* any
* directive rewriting. That ordering is the whole point: reading `<@for item in
* items>` directly is what lets the compiler record that it is a loop over
* `items` binding `item`, instead of rewriting it into a `<template>` element
* and asking the runtime to work that out again.
*
* ## What it refuses
*
* A construct the IR does not model yet aborts the build of that template with
* a {@link IRRefusal} naming the construct. The caller keeps the legacy path
* for that component and the build reports it. There is no partial IR, for the
* same reason there is no partial render program: two descriptions of one
* template disagree eventually, and the disagreement is unattributable.
* @module lib/compiler/ir/build
*/
import { parseHTML } from '../parser/htmlTree.js';
import { createInterpolationRegex } from '../../core/utils/templateUtils.js';
import { isBooleanAttribute } from '../../core/renderer/constants.js';
import {
BindingKind,
IRRefusal,
RefusalReason,
comment,
component,
conditional,
element,
fragment,
deferred,
interpolation,
iteration,
slot,
text,
} from './nodes.js';
/**
* Directive tags the IR does not model yet, mapped to the reason reported.
* @type {Map<string, string>}
*/
const UNMODELLED_TAGS = new Map([
['@suspense', RefusalReason.SUSPENSE],
['@fallback', RefusalReason.SUSPENSE],
['@errorboundary', RefusalReason.ERROR_BOUNDARY],
['@deadlock', RefusalReason.DEADLOCK],
['transition', RefusalReason.TRANSITION],
['resource', RefusalReason.RESOURCE],
['virtuallist', RefusalReason.VIRTUAL_LIST],
['routerview', RefusalReason.ROUTER_VIEW],
]);
/**
* Attributes whose presence means the element needs machinery the IR does not
* model, mapped to the reason reported.
* @type {Array<string[]>}
*/
const UNMODELLED_ATTRS = [
['data-ax-ref', RefusalReason.REF],
['data-ax-validate', RefusalReason.VALIDATION],
['data-ax-router-view', RefusalReason.ROUTER_VIEW],
['data-ax-dyn-attrs', RefusalReason.DYNAMIC_ATTR],
['data-avenx-comp-dynamic', RefusalReason.DYNAMIC_COMPONENT],
['data-ax-transition', RefusalReason.TRANSITION],
];
/**
* Directive attributes that become bindings rather than markup.
* @type {Map<string, string>}
*/
const DIRECTIVE_BINDINGS = new Map([
['data-ax-show', BindingKind.SHOW],
['data-ax-class', BindingKind.CLASS],
['data-ax-html', BindingKind.HTML],
['data-ax-style', BindingKind.STYLE],
]);
/**
* Whether a string contains a template interpolation.
* @param {string} value - The text to test.
* @returns {boolean} True when it contains `{{ }}` or `{{{ }}}`.
*/
function hasInterpolation(value) {
return typeof value === 'string' && value.includes('{{');
}
/**
* Splits text into literal and expression segments, in order.
* @param {string} source - The source text.
* @returns {Array<{expr: string|null, raw: boolean, value: string}>} The segments.
*/
export function splitInterpolations(source) {
const segments = [];
const regex = createInterpolationRegex();
let last = 0;
let match;
while ((match = regex.exec(source)) !== null) {
if (match.index > last) {
segments.push({ expr: null, raw: false, value: source.slice(last, match.index) });
}
const raw = match[1] !== undefined;
segments.push({ expr: (raw ? match[1] : match[2]).trim(), raw, value: '' });
last = regex.lastIndex;
}
if (last < source.length) {
segments.push({ expr: null, raw: false, value: source.slice(last) });
}
return segments;
}
/**
* Finds the offset of a top-level occurrence of a keyword in an expression.
*
* "Top level" means outside quotes and outside every bracket pair, so the `in`
* of `<@for k in Object.keys(map)>` is found and the `in` of an `x in y`
* written inside a call's arguments is not.
* @param {string} source - The text to scan.
* @param {string} word - The keyword to find.
* @returns {number} The offset, or -1.
*/
function findTopLevelWord(source, word) {
let quote = null;
let depth = 0;
for (let i = 0; i < source.length; i++) {
const ch = source[i];
if (quote) {
if (ch === '\\') i++;
else if (ch === quote) quote = null;
continue;
}
if (ch === '"' || ch === "'" || ch === '`') {
quote = ch;
continue;
}
if (ch === '(' || ch === '[' || ch === '{') {
depth++;
continue;
}
if (ch === ')' || ch === ']' || ch === '}') {
if (depth > 0) depth--;
continue;
}
if (depth !== 0) continue;
if (source.startsWith(word, i)) {
const before = i === 0 ? ' ' : source[i - 1];
const after = source[i + word.length] === undefined ? ' ' : source[i + word.length];
if (/\s/.test(before) && /\s/.test(after)) {
return i;
}
}
}
return -1;
}
/**
* Strips a trailing `key="..."` clause from a `<@for>` header.
* @param {string} header - The header text after the list expression.
* @returns {{list: string, key: string|null}} The list source and the key source.
*/
function splitListAndKey(header) {
const match = header.match(/\skey\s*=\s*("([^"]*)"|'([^']*)')\s*$/);
if (!match) {
return { list: header.trim(), key: null };
}
const key = match[2] !== undefined ? match[2] : match[3];
return { list: header.slice(0, match.index).trim(), key: key.trim() || null };
}
/**
* Parses a `<@for>` header into its parts.
*
* Two binding forms, both pre-existing and both preserved exactly:
*
* - `item in list` binds each element to `item`.
* - `[a, b] in pairs` destructures each *element* -- which is an array -- into
* `a` and `b`. It does not mean `(item, index)`, however much it looks like
* the JavaScript it resembles.
*
* Either form also binds `index` implicitly, which is how the loop index has
* always been reached. Both facts are load-bearing for existing applications,
* so they are read out of the previous implementation rather than redesigned
* here; changing either belongs in its own change, with its own migration.
* @param {string} header - The raw header text.
* @returns {{item: string|null, destructure: string[]|null, list: string, key: string|null}} The parts.
* @throws {IRRefusal} When the header is not a loop header.
*/
export function parseForHeader(header) {
const source = (header || '').trim();
// The attribute spelling, `<@for item="user" in="users" key="user.id">`,
// which api-reference/component.md and troubleshooting/errors.md both use.
// It is the same loop as the header spelling and lowers identically; the IR
// refused it as malformed, so every component written that way fell back to
// the string renderer.
const attributeForm = readForAttributes(source);
if (attributeForm) {
return attributeForm;
}
const inAt = findTopLevelWord(source, 'in');
if (inAt === -1) {
throw new IRRefusal(RefusalReason.MALFORMED, `<@for ${source}> has no "in" clause`);
}
const binding = source.slice(0, inAt).trim();
const { list, key } = splitListAndKey(source.slice(inAt + 2));
if (list === '') {
throw new IRRefusal(RefusalReason.MALFORMED, `<@for ${source}> iterates nothing`);
}
const destructured = binding.match(/^\[\s*([A-Za-z_$][\w$]*)\s*(?:,\s*([A-Za-z_$][\w$]*)\s*)?\]$/);
if (destructured) {
return {
item: null,
destructure: destructured[2] ? [destructured[1], destructured[2]] : [destructured[1]],
list,
key,
};
}
if (!/^[A-Za-z_$][\w$]*$/.test(binding)) {
throw new IRRefusal(RefusalReason.MALFORMED, `<@for ${source}> does not bind a name`);
}
return { item: binding, destructure: null, list, key };
}
/**
* Reads the attribute spelling of a loop header.
*
* `item="user" in="users" key="user.id"` means exactly what
* `user in users key="user.id"` means. Only the fully-quoted form is accepted,
* so a header that merely contains the word `in` is still read by the header
* parser.
* @param {string} source - The raw header text.
* @returns {{item: string, destructure: null, list: string, key: string|null}|null}
* The parts, or null when this is not the attribute spelling.
*/
function readForAttributes(source) {
const read = (name) => {
const match = source.match(new RegExp(`(?:^|\\s)${name}\\s*=\\s*("([^"]*)"|'([^']*)')`));
if (!match) return null;
return (match[2] !== undefined ? match[2] : match[3]).trim();
};
const item = read('item');
const list = read('in');
if (!item || !list) {
return null;
}
if (!/^[A-Za-z_$][\w$]*$/.test(item)) {
throw new IRRefusal(RefusalReason.MALFORMED, `<@for ${source}> does not bind a name`);
}
return { item, destructure: null, list, key: read('key') };
}
/**
* Parses an event attribute name into its event and modifiers.
* @param {string} name - The attribute name, including the leading `@`.
* @returns {{event: string, modifiers: string[]}} The parsed parts.
*/
function parseEventName(name) {
const [event, ...modifiers] = name.slice(1).split('.');
return { event, modifiers };
}
/**
* Reads a directive attribute's expression, with or without `{{ }}` around it.
*
* Both spellings are documented and both appear in the wild:
*
* ```html
* <p data-ax-show="isOpen">
* <p data-ax-style="{{ { fontWeight: bold ? '700' : '400' } }}">
* ```
*
* The braces are how an author writes an object literal without it looking
* like an attribute value, so they are stripped here rather than handed to the
* expression parser, which would read `{{` as the start of a block.
* @param {string} value - The attribute value as written.
* @returns {string} The expression source.
*/
function unwrapDirectiveValue(value) {
const segments = splitInterpolations(value);
if (segments.length === 1 && segments[0].expr !== null) {
return segments[0].expr;
}
return value;
}
/**
* Builds an element's bindings and events from its attribute map.
* @param {object} node - The parsed HTML node.
* @returns {{attrs: object, bindings: object[], events: object[]}} The element parts.
* @throws {IRRefusal} When an attribute needs machinery the IR does not model.
*/
function buildAttributes(node) {
const source = node.attrs || {};
const attrs = {};
const bindings = [];
const events = [];
for (const [name, reason] of UNMODELLED_ATTRS) {
if (source[name] !== undefined) {
throw new IRRefusal(reason, `<${node.tagName} ${name}>`);
}
}
for (const [name, value] of Object.entries(source)) {
if (name === 'data-ax-static') continue;
if (name.startsWith('@')) {
const { event, modifiers } = parseEventName(name);
events.push({ event, modifiers, expr: value });
continue;
}
// `:prop="expr"` binds a value; `:[expr]="v"` binds an attribute *name*,
// which has no fixed attribute for a program to address.
if (name.startsWith(':')) {
if (name.includes('[')) {
throw new IRRefusal(RefusalReason.DYNAMIC_ATTR, `<${node.tagName} ${name}>`);
}
bindings.push({ type: BindingKind.ATTR, name: name.slice(1), expr: value });
continue;
}
if (hasInterpolation(name)) {
throw new IRRefusal(RefusalReason.DYNAMIC_ATTR, `<${node.tagName}> interpolated attribute name`);
}
const directive = DIRECTIVE_BINDINGS.get(name);
if (directive) {
bindings.push({ type: directive, name, expr: unwrapDirectiveValue(value) });
continue;
}
if (!hasInterpolation(value)) {
attrs[name] = value;
continue;
}
const segments = splitInterpolations(value);
if (segments.length === 1 && segments[0].expr !== null) {
// One whole expression, so the value keeps its type: a boolean attribute
// can be toggled and null can remove the attribute, neither of which
// survives concatenation into a string.
bindings.push({
type: isBooleanAttribute(name) ? BindingKind.BOOL : BindingKind.ATTR,
name,
expr: segments[0].expr,
});
} else {
bindings.push({
type: BindingKind.ATTR_PARTS,
name,
parts: segments.map((segment) => (segment.expr === null ? segment.value : { expr: segment.expr })),
});
}
}
return { attrs, bindings, events };
}
/**
* Builds the props of a child component from its attribute map.
* @param {object} node - The parsed HTML node.
* @returns {object[]} Prop descriptors.
*/
function buildProps(node) {
const props = [];
for (const [name, value] of Object.entries(node.attrs || {})) {
if (name.startsWith('@')) {
props.push({ name, kind: 'event', expr: value });
continue;
}
const bound = name.startsWith(':');
const propName = bound ? name.slice(1) : name;
if (bound) {
props.push({ name: propName, kind: 'bound', expr: value });
} else if (hasInterpolation(value)) {
const segments = splitInterpolations(value);
if (segments.length === 1 && segments[0].expr !== null) {
props.push({ name: propName, kind: 'bound', expr: segments[0].expr });
} else {
props.push({
name: propName,
kind: 'parts',
parts: segments.map((s) => (s.expr === null ? s.value : { expr: s.expr })),
});
}
} else {
props.push({ name: propName, kind: 'static', value });
}
}
return props;
}
/**
* Whether a tag name refers to a child component rather than an element.
* @param {string} tag - The tag name as written.
* @returns {boolean} True for a PascalCase reference.
*/
function isComponentTag(tag) {
return /^[A-Z][A-Za-z0-9_]*$/.test(tag);
}
/**
* Rejects a conditional header that the tag scan cut in half.
*
* `<@if count > 3>` cannot be read unambiguously: the `>` that means "greater
* than" and the `>` that means "end of tag" are the same character, and nothing
* in the surrounding text distinguishes them. Bracket depth rescues
* `<@for x in xs.filter(a => a.n > 1)>` because the comparison is inside a call;
* a bare comparison has nothing to hide behind.
*
* So the compiler does not guess. A header that was truncated leaves the rest
* of the expression as the first text node of the branch body -- `" 3>"` above
* -- and that shape is what this detects. The author gets the parenthesised
* form, which the scanner reads correctly, rather than a condition that
* silently tests the wrong thing.
* @param {object} node - The parsed directive node.
* @param {string} test - The header text as scanned.
* @throws {IRRefusal} When the header was cut at a comparison.
*/
function assertHeaderNotTruncated(node, test) {
const first = (node.children || [])[0];
if (!first || first.type !== 'text') return;
// A leftover fragment reaches the next `>` without opening an element first.
const leftover = first.content.match(/^([^<]*?)>/);
if (!leftover) return;
const tail = leftover[1].trim();
if (tail === '') return;
throw new IRRefusal(
RefusalReason.MALFORMED,
`<${node.tagName} ${test}> was cut at a ">" -- write it as ` +
`<${node.tagName} (${test} > ${tail})> so the comparison is inside brackets`,
);
}
/**
* Collects an `<@if>` chain starting at `index`, consuming its continuations.
* @param {object[]} siblings - The sibling list being walked.
* @param {number} index - Index of the `<@if>` node.
* @param {function(object[]): object[]} buildChildren - Recursive child builder.
* @returns {{node: object, next: number}} The conditional node and the index to resume at.
*/
function buildConditional(siblings, index, buildChildren) {
const branches = [];
let i = index;
let sawElse = false;
while (i < siblings.length) {
const node = siblings[i];
// Whitespace between `</@if>` and `<@elseif>` is formatting, not content.
// Breaking the chain on it would make an author's indentation decide
// whether their `<@else>` belongs to the `<@if>` above it.
if (node && node.type === 'text' && node.content.trim() === '' && branches.length > 0) {
const following = siblings[i + 1];
const followingTag = following && following.type === 'element' ? (following.tagName || '').toLowerCase() : '';
if (followingTag === '@elseif' || followingTag === '@elif' || followingTag === '@else') {
i++;
continue;
}
break;
}
if (!node || node.type !== 'element') break;
const tag = (node.tagName || '').toLowerCase();
if (tag === '@if' && i !== index) break;
if (tag === '@if' || tag === '@elseif' || tag === '@elif') {
if (sawElse) {
throw new IRRefusal(RefusalReason.MALFORMED, `<${node.tagName}> follows <@else>`);
}
const test = (node.rawAttrs || '').trim();
if (test === '') {
throw new IRRefusal(RefusalReason.MALFORMED, `<${node.tagName}> has no condition`);
}
assertHeaderNotTruncated(node, test);
branches.push({ test, body: fragment(buildChildren(node.children || [])) });
i++;
continue;
}
if (tag === '@else') {
if (sawElse) {
throw new IRRefusal(RefusalReason.MALFORMED, 'two <@else> branches in one chain');
}
sawElse = true;
branches.push({ test: null, body: fragment(buildChildren(node.children || [])) });
i++;
continue;
}
break;
}
return { node: conditional(branches), next: i };
}
/**
* Builds an iteration node from a `<@for>` element.
* @param {object} node - The parsed `<@for>` node.
* @param {function(object[]): object[]} buildChildren - Recursive child builder.
* @returns {object} The iteration node.
*/
function buildIteration(node, buildChildren) {
const parts = parseForHeader(node.rawAttrs);
const body = [];
let empty = null;
for (const child of node.children || []) {
if (child.type === 'element' && (child.tagName || '').toLowerCase() === '@empty') {
if (empty) {
throw new IRRefusal(RefusalReason.MALFORMED, 'two <@empty> blocks in one <@for>');
}
empty = fragment(buildChildren(child.children || []));
continue;
}
body.push(child);
}
return iteration({
list: parts.list,
item: parts.item,
destructure: parts.destructure,
key: parts.key,
body: fragment(buildChildren(body)),
empty,
});
}
/**
* Builds a deferred block from a `<@defer>` element.
*
* `<@placeholder>` is a sibling of the deferred content rather than a wrapper
* around it, so it is separated out here the same way `<@empty>` is separated
* from a loop body.
* @param {object} node - The parsed `<@defer>` node.
* @param {string} when - The resolved trigger.
* @param {function(object[]): object[]} buildChildren - Recursive child builder.
* @returns {object} The defer node.
*/
function buildDefer(node, when, buildChildren) {
const body = [];
let placeholder = null;
for (const child of node.children || []) {
const tag = child.type === 'element' ? (child.tagName || '').toLowerCase() : '';
// `<@loading>` is the spelling core-concepts/defer.md documents; the string
// renderer has always accepted both, and the IR refusing one sent every
// template written that way to the fallback renderer. `<@placeholder>`
// wins when a template somehow carries both, which is the order the
// previous implementation resolved them in.
if (tag === '@placeholder' || tag === '@loading') {
const block = fragment(buildChildren(child.children || []));
if (placeholder && tag === '@placeholder') {
throw new IRRefusal(RefusalReason.MALFORMED, 'two <@placeholder> blocks in one <@defer>');
}
if (!placeholder || tag === '@placeholder') {
placeholder = block;
}
continue;
}
body.push(child);
}
return deferred(when, fragment(buildChildren(body)), placeholder);
}
/**
* Builds the IR for a template.
* @param {string} template - The template source, before directive rewriting.
* @param {object} [options] - Build options.
* @param {string[]} [options.voidTags] - Project-specific void tag names.
* @returns {{ir: object|null, refusal: {reason: string, detail: string}|null}}
* The root fragment, or the reason the template could not be represented.
*/
export function buildTemplateIR(template, options = {}) {
if (typeof template !== 'string' || template.trim() === '') {
return { ir: null, refusal: { reason: RefusalReason.MALFORMED, detail: 'empty template' } };
}
const voidTags = options.voidTags || [];
let parsed;
try {
parsed = parseHTML(template, voidTags);
} catch (error) {
return { ir: null, refusal: { reason: RefusalReason.MALFORMED, detail: `template did not parse: ${error.message}` } };
}
/**
* Builds IR for a sibling list.
* @param {object[]} siblings - Parsed sibling nodes.
* @returns {object[]} IR nodes.
*/
function buildChildren(siblings) {
const out = [];
for (let i = 0; i < siblings.length; i++) {
const node = siblings[i];
if (node.type === 'text') {
for (const segment of splitInterpolations(node.content)) {
if (segment.expr === null) {
if (segment.value !== '') out.push(text(segment.value));
} else {
out.push(interpolation(segment.expr, segment.raw));
}
}
continue;
}
if (node.type === 'comment') {
if (hasInterpolation(node.content)) {
throw new IRRefusal(RefusalReason.UNKNOWN_DIRECTIVE, 'an interpolation inside an HTML comment');
}
out.push(comment(node.content));
continue;
}
const tag = (node.tagName || '').toLowerCase();
const unmodelled = UNMODELLED_TAGS.get(tag);
if (unmodelled) {
throw new IRRefusal(unmodelled, `<${node.tagName}>`);
}
if (tag === '@if') {
const built = buildConditional(siblings, i, buildChildren);
out.push(built.node);
i = built.next - 1;
continue;
}
if (tag === '@elseif' || tag === '@elif' || tag === '@else') {
throw new IRRefusal(RefusalReason.MALFORMED, `<${node.tagName}> without a preceding <@if>`);
}
if (tag === '@for') {
out.push(buildIteration(node, buildChildren));
continue;
}
if (tag === '@defer') {
// `when` is the documented spelling; a bare header is accepted too so
// `<@defer visible>` reads the way the other directives do.
const when = ((node.attrs && node.attrs.when) || (node.rawAttrs || '').trim() || 'idle').trim();
out.push(buildDefer(node, when, buildChildren));
continue;
}
if (tag === '@empty') {
throw new IRRefusal(RefusalReason.MALFORMED, '<@empty> outside a <@for>');
}
if (tag === '@placeholder' || tag === '@loading') {
throw new IRRefusal(RefusalReason.MALFORMED, `<${tag}> outside a <@defer>`);
}
if (tag.startsWith('@')) {
throw new IRRefusal(RefusalReason.UNKNOWN_DIRECTIVE, `<${node.tagName}>`);
}
if (tag === 'slot') {
const name = (node.attrs && node.attrs.name) || 'default';
const fallbackChildren = buildChildren(node.children || []);
out.push(slot(name, fallbackChildren.length > 0 ? fragment(fallbackChildren) : null));
continue;
}
if (isComponentTag(node.tagName)) {
out.push(
component(node.tagName, {
props: buildProps(node),
children: buildChildren(node.children || []),
}),
);
continue;
}
const { attrs, bindings, events } = buildAttributes(node);
out.push(
element(node.tagName, {
attrs,
bindings,
events,
children: buildChildren(node.children || []),
selfClosing: node.isSelfClosing === true,
isStatic: node.attrs && node.attrs['data-ax-static'] !== undefined,
}),
);
}
return out;
}
try {
return { ir: fragment(buildChildren(parsed)), refusal: null };
} catch (error) {
if (error instanceof IRRefusal) {
return { ir: null, refusal: { reason: error.reason, detail: error.detail } };
}
throw error;
}
}
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