tricu

import-plan.ts (1745B)

---

 import type { ModuleStage } from './module-stage.js';
 import { sourceText } from './compiler.js';
 export interface ImportPlan { source: string; statement: string; existing?: { alias: string; start: number; end: number }; }
 // Header meaning comes from the native compiler. Insert at the beginning, which
 // preserves every original character and keeps the directive in the header.
 export function importPlan(source: string, stage: ModuleStage, manifest: string, alias: string): ImportPlan {
   if (!/^[a-f0-9]{64}$/u.test(manifest)) throw new Error('Invalid module manifest');
   if (!/^[A-Za-z_][A-Za-z0-9_]*$/u.test(alias) || alias.length > 128) throw new Error('Use a namespace starting with a letter or underscore, followed by letters, digits or underscores.');
   const statement = `!import ${manifest} as ${alias}\n`;
   const existing = stage.imports.find(([ref]) => ref === manifest);
   if (existing) {
     // Locate a display selection in the compiler-masked header; this has no role
     // in parsing or compiling source. Fall back to selecting the whole source.
     let offset = 0, range = { start: 0, end: source.length };
     const masked = stage.body.split('\n');
     for (const [i, line] of source.split('\n').entries()) {
       if (line !== masked[i] && line.trimStart().startsWith('!import ') && line.includes(manifest)) { range = { start: offset, end: offset + line.length }; break; }
       offset += line.length + 1;
     }
     return { source, statement, existing: { alias: existing[1], ...range } };
   }
   if (stage.imports.some(([, name]) => name === alias)) throw new Error(`Namespace ${alias} is already used by another import.`);
   const next = statement + source;
   sourceText(next);
   return { source: next, statement };
 }