@contrast/rewriter

@contrast/rewriter

Rewrite javascript code with custom rewrite transforms.

For example, Assess will register transforms for + -> contrast_add() so that it can perform propagation via instrumentation of contrast_add().

Example Service Usage

const { Rewriter } = require('.');

const rewriter = new Rewriter({ logger });

rewriter.addTransforms({
  BinaryExpression(path) {
    const method = methodLookups[path.node.operator];
    if (method) {
      path.replaceWith(
        t.callExpression(
          expression('ContrastMethods.%%method%%')({ method }), [
            path.node.left,
            path.node.right
          ]
        )
      );
    }
  }
});

const result = rewriter.rewrite('function add(x, y) { return x + y; }');