[patch][cla] Add Safe Sub-Expressions Support for JsonPath

[kriszyp]

Currently JsonPath? syntax, permits sub-expressions that may be any valid JavaScript? expression. This greatly limits portability because environments that do have full JavaScript? capabilities can not evaluate the expression. Safe sub-expressions use a limited set of operators that can easily be implemented in using any language without requiring a JavaScript? VM. Safe sub-expressions are limited to use the following operators: =, !=, >=, <=, +, -, /, *, ?, : JsonPath? will support a safe sub-expression evaluation syntax checking, which prevents ad-hoc sub-expressions that do not adhere to this set of operators. Safe sub-expression evaluation also prevents arbitrary code execution in JsonPath?. If user supplied JsonPath? queries are executed it is highly recommended that safe sub-expressions evaluation is used to prevent arbitrary JavaScript? execution.

[kriszyp]

Patch

[kriszyp]

I have done numerous other improvements such as: New features:

1. Lenient syntax handling. Right now a simply query user filter expression looks like:

$< 10) We could first of all remove the requirement to start with $, and just let it start with an operator ([ or .). Next, it doesn't seem necessary to require a paranthesis to enclose the expression following the ? on filter expression. We could have ?@.price<10 Then we could also imply that any direct names in a filter expression are properties of @ (the filter items): ?price<10 Finally, we don't really even need the brackets except when more query operations will follow the filter expression: ?price<10 If we had another operation, queries would have to retain the brackets: ?price<10[0:10]

2. Add sorting support. The syntax is like:

firstName ascending by firstName or [\firstName, /lastName] descending by firstName, and then ascending by lastName for firstName ties A query might look like: $< 10[\rating] to find items under $10 and then sorting by rating (highest first) Multiple prioritized columns of sorting could be done like: $< 10[\rating, /author.firstName] which would sort first by rating (descending) and then ties in rating would be sorted by author's firstName in ascending order.

3. Mapping/multi-property selection.

You can do mappings with syntax like: [=newValue] To create a list of authors: $.books[=author] To creates a list of authors who have a book for under $10 we could do: $< 10[={rating:rating, name:author.firstName + ' ' + author.lastName}] This will create a list of objects that have a rating property (from the book's rating), and a name property that is the concatenation of the author's first and last name.

4. General result-level expressions. You can now do general result-level expressions:

$[0].rating > 3 Finds the rating for the first book and returns true or false if the rating is greater than 3.

Consequently this is going to be committed at dojox.json.query.

[Kris Zyp]

(In [14119]) Implementation/fixes #5957