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Copy pathsvelte_preprocess_fuz_code.ts
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269 lines (236 loc) · 7.72 KB
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import { parse, type PreprocessorGroup, type AST } from 'svelte/compiler';
import MagicString from 'magic-string';
import { walk } from 'zimmerframe';
import { should_exclude_path } from '@fuzdev/fuz_util/path.ts';
import { escape_js_string } from '@fuzdev/fuz_util/string.ts';
import {
find_attribute,
extract_static_string,
try_extract_conditional_chain,
build_static_bindings,
resolve_component_names,
handle_preprocess_error,
type ResolvedComponentImport
} from '@fuzdev/fuz_util/svelte_preprocess_helpers.ts';
import { syntax_styler_global } from './syntax_styler_global.ts';
import type { SyntaxStyler } from './syntax_styler.ts';
/**
* Options for `svelte_preprocess_fuz_code`.
*/
export interface PreprocessFuzCodeOptions {
/** File patterns to exclude. */
exclude?: Array<string | RegExp>;
/** Custom `SyntaxStyler` instance. @default syntax_styler_global */
syntax_styler?: SyntaxStyler;
/** Enable in-memory caching. @default true */
cache?: boolean;
/**
* Import sources that resolve to the `Code` component.
* Used to verify that `<Code>` in templates actually refers to `Code.svelte`.
*
* @default ['@fuzdev/fuz_code/Code.svelte']
*/
component_imports?: Array<string>;
/**
* How to handle errors.
* @default 'throw' in CI, 'log' otherwise
*/
on_error?: 'log' | 'throw';
}
/**
* Svelte preprocessor that compiles static `Code` component content at build time,
* replacing runtime syntax styling with pre-rendered HTML.
*
* @param options - `PreprocessFuzCodeOptions` configuration
* @returns a Svelte preprocessor group
*
* @example
* ```ts
* // vite.config.ts
* import {defineConfig} from 'vite';
* import {sveltekit} from '@sveltejs/kit/vite';
* import {vitePreprocess} from '@sveltejs/vite-plugin-svelte';
* import {svelte_preprocess_fuz_code} from '@fuzdev/fuz_code/svelte_preprocess_fuz_code.ts';
*
* export default defineConfig({
* plugins: [
* sveltekit({
* preprocess: [svelte_preprocess_fuz_code(), vitePreprocess()],
* }),
* ],
* });
* ```
*/
export const svelte_preprocess_fuz_code = (
options: PreprocessFuzCodeOptions = {}
): PreprocessorGroup => {
const {
exclude = [],
syntax_styler = syntax_styler_global,
cache = true,
component_imports = ['@fuzdev/fuz_code/Code.svelte'],
on_error = process.env.CI === 'true' ? 'throw' : 'log'
} = options;
// In-memory cache: content+lang hash → styled HTML
const stylize_cache: Map<string, string> = new Map();
return {
name: 'fuz-code',
markup: ({ content, filename }) => {
// Skip excluded files
if (should_exclude_path(filename, exclude)) {
return { code: content };
}
// Quick check: does file import from a known Code component source?
if (!component_imports.some((source) => content.includes(source))) {
return { code: content };
}
const s = new MagicString(content);
const ast = parse(content, { filename, modern: true });
// Resolve which local names map to the Code component
const code_names = resolve_component_names(ast, component_imports);
if (code_names.size === 0) {
return { code: content };
}
const bindings = build_static_bindings(ast);
// Find Code component usages with static content
const transformations = find_code_usages(ast, syntax_styler, code_names, {
cache: cache ? stylize_cache : null,
on_error,
filename,
source: content,
bindings
});
if (transformations.length === 0) {
return { code: content };
}
// Apply transformations
for (const t of transformations) {
s.overwrite(t.start, t.end, t.replacement);
}
return {
code: s.toString(),
map: s.generateMap({ hires: true })
};
}
};
};
interface Transformation {
start: number;
end: number;
replacement: string;
}
interface FindCodeUsagesOptions {
cache: Map<string, string> | null;
on_error: 'log' | 'throw';
filename: string | undefined;
source: string;
bindings: ReadonlyMap<string, string>;
}
/**
* Attempts to style content, using the cache if available.
* Returns the styled HTML, or `null` on error.
*/
const try_stylize = (
text: string,
lang: string,
syntax_styler: SyntaxStyler,
options: FindCodeUsagesOptions
): string | null => {
const cache_key = `${lang}:${text}`;
let html = options.cache?.get(cache_key);
if (html == null) {
try {
html = syntax_styler.stylize(text, lang);
options.cache?.set(cache_key, html);
} catch (error) {
handle_preprocess_error(error, '[fuz-code]', options.filename, options.on_error);
return null;
}
}
return html;
};
/**
* Walks the AST to find `Code` component usages with static `content` props
* and generates transformations to replace them with `dangerous_raw_html`.
*/
const find_code_usages = (
ast: AST.Root,
syntax_styler: SyntaxStyler,
code_names: Map<string, ResolvedComponentImport>,
options: FindCodeUsagesOptions
): Array<Transformation> => {
const transformations: Array<Transformation> = [];
walk(ast.fragment as any, null, {
Component(node: AST.Component, context: { next: () => void }) {
// Always recurse into children - without this, Code components
// nested inside other components would be missed, because zimmerframe
// does not auto-recurse when a visitor is defined for a node type.
context.next();
if (!code_names.has(node.name)) return;
// Skip if spread attributes present — can't determine content statically
if (node.attributes.some((attr) => attr.type === 'SpreadAttribute')) return;
const content_attr = find_attribute(node, 'content');
if (!content_attr) return;
// Skip if already preprocessed or a custom syntax_styler is provided
if (find_attribute(node, 'dangerous_raw_html') || find_attribute(node, 'syntax_styler')) {
return;
}
// Resolve language - must be static and supported
const lang_attr = find_attribute(node, 'lang');
const lang_value = lang_attr
? extract_static_string(lang_attr.value, options.bindings)
: 'svelte';
if (lang_value === null) return;
if (!syntax_styler.has_lang(lang_value)) return;
// Try simple static string
const content_value = extract_static_string(content_attr.value, options.bindings);
if (content_value !== null) {
const html = try_stylize(content_value, lang_value, syntax_styler, options);
if (html === null || html === content_value) return;
transformations.push({
start: content_attr.start,
end: content_attr.end,
replacement: `dangerous_raw_html={'${escape_js_string(html)}'}`
});
return;
}
// Try conditional chain (handles both simple and nested ternaries)
const chain = try_extract_conditional_chain(
content_attr.value,
options.source,
options.bindings
);
if (chain) {
// Style all branches
const styled: Array<{ html: string; original: string }> = [];
let any_changed = false;
for (const branch of chain) {
const html = try_stylize(branch.value, lang_value, syntax_styler, options);
if (html === null) return;
if (html !== branch.value) any_changed = true;
styled.push({ html, original: branch.value });
}
if (!any_changed) return;
// Build nested ternary expression for dangerous_raw_html
// chain: [{test_source: 'a', value: ...}, {test_source: 'b', value: ...}, {test_source: null, value: ...}]
// → a ? 'html_a' : b ? 'html_b' : 'html_c'
let expr = '';
for (let i = 0; i < chain.length; i++) {
const branch = chain[i]!;
const html = styled[i]!.html;
if (branch.test_source !== null) {
expr += `${branch.test_source} ? '${escape_js_string(html)}' : `;
} else {
expr += `'${escape_js_string(html)}'`;
}
}
transformations.push({
start: content_attr.start,
end: content_attr.end,
replacement: `dangerous_raw_html={${expr}}`
});
}
}
});
return transformations;
};