std.jgrandson

[Dmitry Olshansky via Digitalmars-d]

03-Aug-2014 21:40, Andrei Alexandrescu пишет:
> On 8/3/14, 10:19 AM, Sean Kelly wrote:
>> I don't want to pay for anything I don't use.  No allocations should
>> occur within the parser and it should simply slice up the input.
>
> What to do about arrays and objects, which would naturally allocate
> arrays and associative arrays respectively? What about strings with
> backslash-encoded characters?
>

SAX-style would imply that array is "parsed" by calling 6 user-defined 
callbacks inside of a parser:
startArray, endArray, startObject, endObject, id and value.

A simplified pseudo-code of JSON-parser inner loop is then:

if(cur == '[')
        startArray();
else if(cur == '{'){
	startObject();
else if(cur == '}')
	endObject();
else if(cur == ']')
	endArray();
else{
      if(expectObjectKey){
	id(parseAsIdentifier());
      }
      else
	value(parseAsValue());
}

This is as barebones as it can get and is very fast in practice esp. in 
context of searching/extracting/matching specific sub-tries of JSON 
documents.

-- 
Dmitry Olshansky