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initial commit, support preconditions
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‎.babelrc

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{
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"presets": [
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"stage-0",
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"es2015"
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],
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"plugins": [
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"typecheck"
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]
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}

‎.gitignore

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.settings
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node_modules
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lib
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lib-checked
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*.transformed
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npm-debug.log

‎.npmignore

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‎.travis.yml

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language: node_js
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node_js:
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- "0.12"
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- "iojs"
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- "4.2.1"

‎LICENSE.md

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# The MIT License (MIT)
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Copyright (c) 2015 codemix.com
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in
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all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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THE SOFTWARE.

‎README.md

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# Babel Contracts
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This is a [Babel](https://babeljs.io/) plugin for design by contract for JavaScript.
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[![Build Status](https://travis-ci.org/codemix/babel-plugin-contracts.svg)](https://travis-ci.org/codemix/babel-plugin-contracts)
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# What?
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Dunno yet.
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# Installation
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Install via [npm](https://npmjs.org/package/babel-plugin-contracts).
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```sh
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npm install --save-dev babel-plugin-contracts
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```
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Then, in your babel configuration (usually in your `.babelrc` file), add `"contracts"` to your list of plugins:
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```json
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{
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"plugins": ["contracts"]
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}
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```
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# License
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Published by [codemix](http://codemix.com/) under a permissive MIT License, see [LICENSE.md](./LICENSE.md).
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‎package.json

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{
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"name": "babel-plugin-contracts",
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"version": "3.2.1",
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"description": "Transforms flow type annotations into runtime type checks.",
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"main": "lib/index.js",
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"scripts": {
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"build": "babel --plugins syntax-flow,transform-flow-strip-types -d ./lib ./src",
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"build-typed": "npm run build && babel --plugins ./lib,syntax-flow,transform-flow-strip-types -d ./lib-checked ./src",
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"prepublish": "npm run build",
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"pretest": "npm run build",
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"test": "mocha ./test/index.js",
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"test-checked": "npm run build-typed && CONTRACTS_USE_LIBCHECKED=1 mocha ./test/index.js",
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"watch": "NODE_WATCH=1 mocha --watch"
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},
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"repository": {
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"type": "git",
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"url": "https://github.com/codemix/babel-plugin-contracts"
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},
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"keywords": [
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"babel",
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"babel-plugin",
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"design by contract",
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"types",
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"typing",
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"contracts",
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"type check",
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"dbyc"
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],
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"author": "Charles Pick <[email protected]>",
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"license": "MIT",
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"bugs": {
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"url": "https://github.com/codemix/babel-plugin-contracts/issues"
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},
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"homepage": "https://github.com/codemix/babel-plugin-contracts",
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"devDependencies": {
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"babel-cli": "^6.1.0",
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"babel-core": "^6.1.0",
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"babel-generator": "^6.1.2",
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"babel-plugin-syntax-class-properties": "^6.1.18",
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"babel-plugin-syntax-flow": "^6.0.14",
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"babel-plugin-transform-es2015-modules-commonjs": "^6.1.3",
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"babel-plugin-transform-flow-strip-types": "^6.0.14",
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"babel-plugin-typecheck": "^3.2.1",
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"babel-polyfill": "^6.0.16",
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"babel-preset-es2015": "^6.1.0",
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"babel-preset-react": "^6.1.0",
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"babel-preset-stage-0": "^6.1.18",
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"babel-preset-stage-1": "^6.1.0",
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"mocha": "~2.2.4",
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"should": "^6.0.1"
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}
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}

‎src/index.js

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import generate from "babel-generator";
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type Plugin = {
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visitor: Visitors
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};
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type PluginParams = {
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types: Object;
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template: (source: string) => (ids: Object) => Node;
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};
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type Visitors = {
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[key: string]: Visitor
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}
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type Visitor = (path: NodePath) => void;
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type Node = {
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type: string;
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};
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type Literal = {
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type: 'StringLiteral' | 'BooleanLiteral' | 'NumericLiteral' | 'NullLiteral' | 'RegExpLiteral'
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};
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type Identifier = {
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type: string;
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name: string;
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};
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type Scope = {};
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type NodePath = {
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type: string;
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node: Node;
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scope: Scope;
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};
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/**
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* # Design By Contract Transformer
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*/
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export default function ({types: t, template}: PluginParams): Plugin {
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const PRECONDITION_NAME = 'pre';
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const POSTCONDITION_NAME = 'post';
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const INVARIANT_NAME = 'invariant';
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const preconditionAsserter: (ids: {[key: string]: Node}) => Node = template(`
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if (!condition) {
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throw new Error(message);
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}
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`);
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const functionVisitor: Visitors = {
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Function (path: NodePath): void {
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// This will be handled by the outer visitor, so skip it.
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path.skip();
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},
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LabeledStatement (path: NodePath): void {
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const label: NodePath = path.get('label');
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if (label.node.name === PRECONDITION_NAME) {
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assemblePrecondition(path);
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}
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}
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};
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function assemblePrecondition (path: NodePath): void {
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const body: NodePath = path.get('body');
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const fn: NodePath = path.getFunctionParent();
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const name: string = fn.node.id ? `"${fn.node.id.name}" `: ' ';
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body.traverse({
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VariableDeclaration (item: NodePath): void {
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throw path.buildCodeFrameError(`Preconditions cannot have side effects.`);
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},
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Function (item: NodePath): void {
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throw path.buildCodeFrameError(`Preconditions cannot have side effects.`);
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},
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AssignmentExpression (item: NodePath): void {
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throw path.buildCodeFrameError(`Preconditions cannot have side effects.`);
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},
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UpdateExpression (item: NodePath): void {
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throw path.buildCodeFrameError(`Preconditions cannot have side effects.`);
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},
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ExpressionStatement (statement: NodePath): void {
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let condition: NodePath = statement.get('expression');
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let message;
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if (condition.isSequenceExpression()) {
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const expressions = condition.get('expressions');
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condition = expressions[0];
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message = expressions[1];
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}
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else {
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message = t.stringLiteral(`Function ${name}precondition failed: ${generate(condition.node).code}`);
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}
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statement.replaceWith(preconditionAsserter({
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condition,
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message
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}));
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}
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});
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if (body.isBlockStatement()) {
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path.replaceWithMultiple(path.get('body').node.body);
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}
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else {
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path.replaceWith(path.get('body'));
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}
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}
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function expression (input: string): Function {
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const fn: Function = template(input);
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return function (...args) {
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const node: Node = fn(...args);
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return getExpression(node);
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};
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}
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return {
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visitor: {
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Function (path: NodePath): void {
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if (path.isArrowFunctionExpression() && !path.get('body').isBlockStatement()) {
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// Naked arrow functions cannot contain contracts.
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return;
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}
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path.traverse(functionVisitor);
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}
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}
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};
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}

‎test-polyfill.js

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require("babel-core/register")({
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"presets": ["stage-1", "es2015"],
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"plugins": [
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//"syntax-flow",
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"transform-flow-strip-types"
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]
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});

‎test/fixtures/bad-precondition-with-assignment.js

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export default function demo (input) {
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pre: {
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typeof input === 'string';
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input = false;
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}
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return input.length;
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}

‎test/fixtures/bad-precondition-with-let.js

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export default function demo (input) {
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pre: {
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let i = 0;
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typeof input[i] === 'string';
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}
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return input.length;
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}

‎test/fixtures/bad-precondition-with-updateexpr.js

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let thing = 0;
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export default function demo (input) {
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pre: {
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thing++;
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}
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return input.length;
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}

‎test/fixtures/precondition-multiple.js

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export default function demo (input) {
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pre: {
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typeof input === 'string';
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input.length > 3;
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input.length < 6;
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}
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return input.length;
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}

‎test/fixtures/precondition-with-message.js

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export default function demo (input) {
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pre: {
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typeof input === 'string', "Input must be a string";
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}
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return input.length;
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}

‎test/fixtures/precondition.js

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export default function demo (input) {
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pre: {
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typeof input === 'string';
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}
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return input.length;
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}

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