feat(@gabliam/expression): begin expression package

packages/expression/README.md

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+[![Build Status][build-image]][build-url]
+[![NPM version][npm-image]][npm-url]
+
+
+# Gabliam amqp
+
+Gabliam plugin for add amqp.
+
+# License
+
+  MIT
+
+[build-image]: https://img.shields.io/travis/gabliam/gabliam/master.svg?style=flat-square
+[build-url]: https://travis-ci.org/gabliam/gabliam
+[npm-image]: https://img.shields.io/npm/v/@gabliam/amqp.svg?style=flat-square
+[npm-url]: https://github.com/gabliam/amqp

packages/expression/package.json

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+{
+  "name": "@gabliam/expression",
+  "version": "6.1.0",
+  "description": "expression parser",
+  "main": "lib/index.js",
+  "typings": "lib/index.d.ts",
+  "module": "lib/index.js",
+  "scripts": {
+    "build": "rimraf lib && tsc -p tsconfig.build.json"
+  },
+  "files": [
+    "lib",
+    "src"
+  ],
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/gabliam/gabliam.git"
+  },
+  "keywords": [
+    "amqp",
+    "gabliam"
+  ],
+  "author": "David Touzet <dtouzet@gmail.com>",
+  "license": "MIT",
+  "bugs": {
+    "url": "https://github.com/gabliam/gabliam/issues"
+  },
+  "homepage": "https://github.com/gabliam/gabliam/tree/master/packages/amqp#readme",
+  "peerDependencies": {
+    "@gabliam/core": "^6.1.0"
+  },
+  "devDependencies": {
+    "@types/escodegen": "^0.0.6",
+    "@types/esprima": "^4.0.1",
+    "@types/node": "^8.0.14"
+  },
+  "dependencies": {
+    "escodegen": "^1.9.0",
+    "esprima": "^4.0.0",
+    "tslib": "^1.8.0"
+  }
+}

packages/expression/src/expression-parser.ts

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+import * as esprima from 'esprima';
+import { ExpressionStatement } from 'estree';
+import { Expression } from './expression';
+
+export class ExpressionParser {
+  constructor(private context: object = {}) {
+  }
+
+  parseExpression(input: string) {
+    const program = esprima.parseScript(input);
+    const ast = (<ExpressionStatement>program.body[0]).expression;
+    return new Expression(ast, this.context);
+  }
+}

packages/expression/src/expression.ts

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+import { Expression as AstExpression } from 'estree';
+import { Parser } from './parser';
+
+export class Expression {
+  private parser: Parser;
+
+  constructor(ast: AstExpression, private context: object = {}) {
+    this.parser = new Parser(ast);
+  }
+
+  getValue<T>(vars: object = {}): T | undefined | null {
+    return this.parser.parse({
+      ...this.context,
+      ...vars
+    });
+  }
+}