Document bindings (#119)

* Instructions for WASM/JS binding

Signed-off-by: Anand Krishnamoorthi <anakrish@microsoft.com>

* Document Python, WASM/JS bindings

Signed-off-by: Anand Krishnamoorthi <anakrish@microsoft.com>

---------

Signed-off-by: Anand Krishnamoorthi <anakrish@microsoft.com>

bindings/wasm/README.md

@@ -6,9 +6,13 @@
    interpreter written in Rust.
   - *Rigorous* - A rigorous enforcer of well-defined Rego semantics.
 
+`regorusjs` is Regorus compiled into WASM.
+
 See [Repository](https://github.com/microsoft/regorus).
 
-`regorusjs` is Regorus compiled into WASM.
+To build this binding, see [building](https://github.com/microsoft/regorus/bindings/wasm/building.md)
+
+
 
 ## Usage
 

bindings/wasm/building.md

@@ -0,0 +1,34 @@
+
+- Install `wasm-pack`
+  ```
+  cargo install wasm-pack
+  ```
+
+- Build `regorusjs` for nodejs.
+  ```
+  cd bindings/wasm
+  wasm-pack build --target nodejs --release
+  ```
+
+- Install [nodejs](https://nodejs.org/en/download)
+
+- Run the test script
+  ```
+  $ node test.js
+  \\{
+  \\  "result": [
+  \\    {
+  \\      "expressions": [
+  \\        {
+  \\          "value": "Hello, World!",
+  \\          "text": "data.test.message",
+  \\          "location": {
+  \\            "row": 1,
+  \\            "col": 1
+  \\          }
+  \\        }
+  \\      ]
+  \\    }
+  \\   ]
+  \\}
+  ```

bindings/wasm/test.js

@@ -0,0 +1,47 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+var regorus = require('./pkg/regorusjs')
+
+// Create an engine.
+var engine = new regorus.Engine();
+
+// Add Rego policy.
+engine.add_policy(
+    // Associate this file name with policy
+    'hello.rego',
+    
+    // Rego policy
+`
+  package test
+  
+  # Join messages
+  message = concat(", ", [input.message, data.message])
+`)
+
+// Set policy data
+engine.add_data_json(`
+ {
+    "message" : "World!"
+ }
+`)
+
+// Set policy input
+engine.set_input_json(`
+ {
+	"message" : "Hello"
+ }
+`)
+
+// Eval query
+results = engine.eval_query('data.test.message')
+
+// Display
+console.log(results)
+
+// Convert results to object
+results = JSON.parse(results)
+
+// Process result
+console.log(results.result[0].expressions[0].value)
+