Method evaluateCode

packages/compiler/src/output/output_jit.ts:60–85

* Evaluate a piece of JIT generated code. * @param sourceUrl The URL of this generated code. * @param ctx A context object that contains an AST of the code to be evaluated. * @param vars A map containing the names and values of variables that the evaluated code might * reference. * @p

(
    sourceUrl: string,
    ctx: EmitterVisitorContext,
    vars: {[key: string]: any},
    createSourceMap: boolean,
  )

   * @returns The result of evaluating the code.
   */
  evaluateCode(
    sourceUrl: string,
    ctx: EmitterVisitorContext,
    vars: {[key: string]: any},
    createSourceMap: boolean,
  ): any {
    let fnBody = `"use strict";${ctx.toSource()}\n//# sourceURL=${sourceUrl}`;
    const fnArgNames: string[] = [];
    const fnArgValues: any[] = [];
    for (const argName in vars) {
      fnArgValues.push(vars[argName]);
      fnArgNames.push(argName);
    }
    if (createSourceMap) {
      // using `new Function(...)` generates a header, 1 line of no arguments, 2 lines otherwise
      // E.g. ```
      // function anonymous(a,b,c
      // /**/) { ... }```
      // We don't want to hard code this fact, so we auto detect it via an empty function first.
      const emptyFn = newTrustedFunctionForJIT(...fnArgNames.concat('return null;')).toString();
      const headerLines = emptyFn.slice(0, emptyFn.indexOf('return null;')).split('\n').length - 1;
      fnBody += `\n${ctx.toSourceMapGenerator(sourceUrl, headerLines).toJsComment()}`;
    }
    const fn = newTrustedFunctionForJIT(...fnArgNames.concat(fnBody));
    return this.executeFunction(fn, fnArgValues);
  }

  /**
   * Execute a JIT generated function by calling it.