tests, docs

example/eval.js

@@ -1,11 +1,7 @@
-var evaluate = require('../');
+var evaluate = require('static-eval');
 var parse = require('esprima').parse;
 
-var src = '[1,2,3+4*10+n,foo(3+5),obj[""+"x"].y]';
+var src = process.argv.slice(2).join(' ');
 var ast = parse(src).body[0].expression;
 
-console.log(evaluate(ast, {
-    n: 6,
-    foo: function (x) { return x * 100 },
-    obj: { x: { y: 555 } }
-}));
+console.log(evaluate(ast));

example/vars.js

@@ -0,0 +1,11 @@
+var evaluate = require('../');
+var parse = require('esprima').parse;
+
+var src = '[1,2,3+4*10+n,foo(3+5),obj[""+"x"].y]';
+var ast = parse(src).body[0].expression;
+
+console.log(evaluate(ast, {
+    n: 6,
+    foo: function (x) { return x * 100 },
+    obj: { x: { y: 555 } }
+}));

index.js

@@ -1,6 +1,3 @@
-var parse = require('esprima').parse;
-var deparse = require('escodegen').generate;
-
 module.exports = function (ast, vars) {
     if (!vars) vars = {};
     var FAIL = {};

readme.markdown

@@ -0,0 +1,79 @@
+# static-eval
+
+evaluate statically-analyzable expressions
+
+# example
+
+``` js
+var evaluate = require('static-eval');
+var parse = require('esprima').parse;
+
+var src = process.argv[2];
+var ast = parse(src).body[0].expression;
+
+console.log(evaluate(ast));
+```
+
+If you stick to simple expressions, the result is statically analyzable:
+
+```
+$ node '7*8+9'
+65
+$ node eval.js '[1,2,3+4*5-(5*11)]'
+[ 1, 2, -32 ]
+```
+
+but if you use statements, undeclared identifiers, or syntax, the result is no
+longer statically analyzable and `evaluate()` returns `undefined`:
+
+```
+$ node eval.js '1+2+3*n'
+undefined
+$ node eval.js 'x=5; x*2'
+undefined
+$ node eval.js '5-4*3'
+-7
+```
+
+You can also declare variables and functions to use in the static evaluation:
+
+``` js
+var evaluate = require('static-eval');
+var parse = require('esprima').parse;
+
+var src = '[1,2,3+4*10+n,foo(3+5),obj[""+"x"].y]';
+var ast = parse(src).body[0].expression;
+
+console.log(evaluate(ast, {
+    n: 6,
+    foo: function (x) { return x * 100 },
+    obj: { x: { y: 555 } }
+}));
+```
+
+# methods
+
+``` js
+var evaluate = require('static-eval');
+```
+
+## evaluate(ast, vars={})
+
+Evaluate the [esprima](https://npmjs.org/package/esprima)-parsed abstract syntax
+tree object `ast` with an optional collection of variables `vars` to use in the
+static expression resolution.
+
+If the expression contained in `ast` can't be statically resolved, `evaluate()`
+returns undefined.
+
+# install
+
+With [npm](https://npmjs.org) do:
+
+```
+npm install static-eval
+```
+
+# license
+
+MIT

test/eval.js

@@ -0,0 +1,29 @@
+var test = require('tape');
+var evaluate = require('../');
+var parse = require('esprima').parse;
+
+test('resolved', function (t) {
+    t.plan(1);
+
+    var src = '[1,2,3+4*10+n,foo(3+5),obj[""+"x"].y]';
+    var ast = parse(src).body[0].expression;
+    var res = evaluate(ast, {
+        n: 6,
+        foo: function (x) { return x * 100 },
+        obj: { x: { y: 555 } }
+    });
+    t.deepEqual(res, [ 1, 2, 49, 800, 555 ]);
+});
+
+test('unresolved', function (t) {
+    t.plan(1);
+
+    var src = '[1,2,3+4*10*z+n,foo(3+5),obj[""+"x"].y]';
+    var ast = parse(src).body[0].expression;
+    var res = evaluate(ast, {
+        n: 6,
+        foo: function (x) { return x * 100 },
+        obj: { x: { y: 555 } }
+    });
+    t.equal(res, undefined);
+});