feat(mf2): Support u:locale option (unicode-org/message-format-wg#846)

Author: XM5jDcsHTyGJtQqlCi

mf2/messageformat/src/data-model/format-markup.ts

@@ -1,6 +1,7 @@
+import { MessageResolutionError } from '../errors.js';
 import type { Context } from '../format-context.js';
 import type { MessageMarkupPart } from '../formatted-parts.js';
-import { resolveValue } from './resolve-value.js';
+import { getValueSource, resolveValue } from './resolve-value.js';
 import type { Markup } from './types.js';
 
 export function formatMarkup(
@@ -13,12 +14,17 @@ export function formatMarkup(
   if (options?.size) {
     part.options = {};
     for (const [name, value] of options) {
-      let rv = resolveValue(ctx, value);
-      if (typeof rv === 'object' && typeof rv?.valueOf === 'function') {
-        const vv = rv.valueOf();
-        if (vv !== rv) rv = vv;
+      if (name === 'u:locale') {
+        const msg = `The option ${name} is not valid for markup`;
+        const optSource = getValueSource(value);
+        ctx.onError(new MessageResolutionError('bad-option', msg, optSource));
+      } else {
+        let rv = resolveValue(ctx, value);
+        if (typeof rv === 'object' && typeof rv?.valueOf === 'function') {
+          rv = rv.valueOf();
+        }
+        part.options[name] = rv;
       }
-      part.options[name] = rv;
     }
   }
   return part;

mf2/messageformat/src/data-model/function-context.ts

@@ -1,17 +1,30 @@
 import type { Context } from '../format-context.js';
+import { resolveValue } from './resolve-value.js';
+import { Options } from './types.js';
 
 export class MessageFunctionContext {
   #ctx: Context;
+  #locales: string[];
   readonly source: string;
-  constructor(ctx: Context, source: string) {
+  constructor(ctx: Context, source: string, options: Options | undefined) {
     this.#ctx = ctx;
+    const lc = options?.get('u:locale');
+    if (lc) {
+      let rl = resolveValue(ctx, lc);
+      if (typeof rl === 'object' && typeof rl?.valueOf === 'function') {
+        rl = rl.valueOf();
+      }
+      this.#locales = Array.isArray(rl) ? rl.map(String) : [String(rl)];
+    } else {
+      this.#locales = ctx.locales;
+    }
     this.source = source;
   }
   get localeMatcher() {
     return this.#ctx.localeMatcher;
   }
   get locales() {
-    return this.#ctx.locales.slice();
+    return this.#locales.slice();
   }
   get onError() {
     return this.#ctx.onError;

mf2/messageformat/src/data-model/resolve-function-ref.ts

@@ -25,7 +25,7 @@ export function resolveFunctionRef(
     if (!rf) {
       throw new MessageError('unknown-function', `Unknown function :${name}`);
     }
-    const msgCtx = new MessageFunctionContext(ctx, source);
+    const msgCtx = new MessageFunctionContext(ctx, source, options);
     const opt = resolveOptions(ctx, options);
     const res = rf(msgCtx, opt, ...fnInput);
     if (
@@ -51,7 +51,9 @@ function resolveOptions(ctx: Context, options: Options | undefined) {
   const opt: Record<string, unknown> = Object.create(null);
   if (options) {
     for (const [name, value] of options) {
-      opt[name] = resolveValue(ctx, value);
+      if (name !== 'u:locale') {
+        opt[name] = resolveValue(ctx, value);
+      }
     }
   }
   return opt;

mf2/messageformat/src/data-model/resolve-value.ts

@@ -19,6 +19,10 @@ export function resolveValue(
 }
 
 /** @internal */
+export function getValueSource(value: Literal | VariableRef): string;
+export function getValueSource(
+  value: Literal | VariableRef | undefined
+): string | undefined;
 export function getValueSource(value: Literal | VariableRef | undefined) {
   switch (value?.type) {
     case 'literal':