create a ipynbv3 json schema and a validator

cf http://json-schema.org/
http://tools.ietf.org/html/draft-zyp-json-schema-03

autogenerated from
http://www.jsonschema.net/index.html#
then tweeked.

This version makes all our notedooks in docs/example/notebooks valid

IPython/nbformat/v3/v3.withref.json

@@ -0,0 +1,166 b''
+{
+    "description": "custom json structure with references to generate notebook schema",
+    "notebook":{
+      "type": "object",
+      "description": "notebook v3.0 root schema",
+      "$schema": "http://json-schema.org/draft-03/schema",
+      "id": "#notebook",
+      "required": true,
+      "additionalProperties": false,
+      "properties":{
+        "metadata": {
+          "type": "object",
+          "id": "metadata",
+          "required": true,
+          "description": "the metadata atribute can contain any additionnal information",
+          "additionalProperties": true,
+          "properties":{
+            "name": {
+              "id": "name",
+              "description": "the title of the notebook",
+              "type": "string",
+              "id": "name",
+              "required": true
+            }
+          }
+        },
+        "nbformat_minor": {
+          "description": "Notebook format, minor number. Incremented for slight variation of notebook format.",
+          "type": "number",
+          "id": "nbformat_minor",
+          "required": true
+        },
+        "nbformat": {
+          "description": "Notebook format, major number. Incremented between backward incompatible change is introduced.",
+          "type": "number",
+          "id": "nbformat",
+          "required": true
+        },
+        "worksheets": {
+          "description": "Array of worksheet, not used by the current implementation of ipython yet",
+          "type": "array",
+          "id": "worksheets",
+          "required": true,
+          "items": {"$ref": "/worksheet"}
+        }
+      }
+    },
+
+    "worksheet": {
+      "additionalProperties": false,
+      "properties":{
+        "cells": {
+          "type": "array",
+          "$schema": "http://json-schema.org/draft-03/schema",
+          "description": "array of cells of the current worksheet",
+          "id": "#cells",
+          "required": true,
+          "items": {"$ref": "/any_cell"}
+
+        },
+        "metadata": {
+          "type": "object",
+          "description": "metadata of the current worksheet",
+          "id": "metadata",
+          "required": true
+        }
+      }
+    },
+
+    "text_cell": {
+      "type": "object",
+      "description": "scheme for text cel and childrenm (level only optionnal argument for HEader cell)",
+      "$schema": "http://json-schema.org/draft-03/schema",
+      "id": "#cell",
+      "required": true,
+      "additionalProperties": false,
+      "properties":{
+        "cell_type": {
+          "type": "string",
+          "id": "cell_type",
+          "required": true
+        },
+        "level": {
+          "type": "number",
+          "id": "level",
+          "required": false
+        },
+        "metadata": {
+          "type": "object",
+          "id": "metadata",
+          "required": true
+        },
+        "source": {
+          "description": "for code cell, the source code",
+          "type": "array",
+          "id": "source",
+          "required": true,
+          "items":
+            {
+              "type": "string",
+              "description": "each item represent one line of the source code written, terminated by \n",
+              "id": "0",
+              "required": true
+            }
+        }
+      }
+
+    },
+
+    "any_cell": {
+        "description": "Meta cell type that match any cell type",
+        "type": [{"$ref": "/text_cell"},{"$ref":"/code_cell"}],
+        "$schema": "http://json-schema.org/draft-03/schema"
+    },
+
+    "code_cell":{
+      "type": "object",
+      "$schema": "http://json-schema.org/draft-03/schema",
+      "description": "Cell used to execute code",
+      "id": "#cell",
+      "required": true,
+      "additionalProperties": false,
+      "properties":{
+        "cell_type": {
+          "type": "string",
+          "id": "cell_type",
+          "required": true
+        },
+        "metadata": {
+          "type": "object",
+          "id": "metadata",
+          "required": true
+        },
+        "collapsed": {
+          "type": "boolean",
+          "required": true
+        },
+        "input": {
+          "description": "user input for text cells",
+          "type": "array",
+          "id": "input",
+          "required": true,
+          "items":
+            {
+              "type": "string",
+              "id": "input",
+              "required": true
+            }
+        },
+        "outputs": {
+            "description": "output for code cell, to be definied",
+            "required": true,
+            "type": "array"
+        },
+        "prompt_number": {
+            "type": ["number","string"],
+            "minimum": 0
+        },
+        "language": {
+            "type": "string",
+            "required": true
+        }
+      }
+
+    }
+}

IPython/nbformat/v3/validator.py

@@ -0,0 +1,88 b''
+#!/usr/bin/env python
+# -*- coding: utf8 -*-
+
+from jsonschema import  Validator, validate, ValidationError
+import jsonpointer
+import argparse
+import traceback
+import json
+
+v = Validator();
+def nbvalidate(nbjson, schema='v3.withref.json', key=None,verbose=True):
+    v3schema = resolve_ref(json.load(open(schema,'r')))
+    if key :
+        v3schema = jsonpointer.resolve_pointer(v3schema,key)
+    errors = 0
+    for error in v.iter_errors(nbjson, v3schema):
+        errors = errors + 1
+        if verbose:
+            print(error)
+    return errors
+
+def resolve_ref(json, base=None):
+    """return a json with resolved internal references
+
+    only support local reference to the same json
+    """
+    if not base :
+        base = json
+
+    temp = None
+    if type(json) is list:
+        temp = [];
+        for item in json:
+            temp.append(resolve_ref(item, base=base))
+    elif type(json) is dict:
+        temp = {};
+        for key,value in json.iteritems():
+            if key == '$ref':
+                return resolve_ref(jsonpointer.resolve_pointer(base,value), base=base)
+            else :
+                temp[key]=resolve_ref(value, base=base)
+    else :
+        return json
+    return temp
+
+def convert(namein, nameout, indent=2):
+    """resolve the references of namein, save the result in nameout"""
+    jsn = None
+    with open(namein) as file :
+        jsn = json.load(file)
+    v = resolve_ref(jsn, base=jsn)
+    x = jsonpointer.resolve_pointer(v, '/notebook')
+    with open(nameout,'w') as file:
+        json.dump(x,file,indent=indent)
+
+
+if __name__ == '__main__':
+    parser = argparse.ArgumentParser()
+    parser.add_argument('-s', '--schema',
+                    type=str, default='v3.withref.json')
+
+    parser.add_argument('-k', '--key',
+                    type=str, default='/notebook',
+                    help='subkey to extract json schema from json file')
+
+    parser.add_argument("-v", "--verbose", action="store_true",
+                    help="increase output verbosity")
+
+    parser.add_argument('filename',
+            type=str,
+            help="file to validate",
+            nargs='*',
+            metavar='names')
+
+    args = parser.parse_args()
+    for name in args.filename :
+        nerror = nbvalidate(json.load(open(name,'r')),
+                            schema=args.schema,
+                            key=args.key,
+                            verbose=args.verbose)
+        if nerror is 0:
+            print u"[Pass]",name
+        else :
+            print u"[    ]",name,'(%d)'%(nerror)
+        if args.verbose :
+            print '=================================================='
+
+