json/parse.bend checks

raw source on the hub · import 0x729eecea86ea5a2cdba3a2856a313bca/json/parse.bend as Parse

json/parse: tokens to a value, one token per step, over an explicit stack of open arrays and objects: a loop, with no fuel and no recursion on the value. Lenient about commas and colons; strict about nesting and a single root.

3 imports

import Base
import ./value.bend as V
import ./lex.bend as Lex

Types

type Frame source · line 10 · raw

Data

an open array (its items, reversed) or an open object (its pairs, reversed, and the key awaiting its value)

FArr

@items:0x729eecea86ea5a2cdba3a2856a313bca/json/value.Json -> Frame

FObj

@pairs:0x729eecea86ea5a2cdba3a2856a313bca/json/value.Json -> @key:Maybe<&2, String> -> Frame

type P source · line 15 · raw

Data

the parser's state: an error was seen, the finished root, the open frames

P

@bad:Bool -> @root:Maybe<&2, 0x729eecea86ea5a2cdba3a2856a313bca/json/value.Json> -> @stack:List<&2, Frame> -> P

Definitions

def word source · line 19 · raw

@+raw:String -> 0x729eecea86ea5a2cdba3a2856a313bca/json/value.Json

a bare word as a value: null, true, false, else a number kept as text

def put source · line 25 · raw

@stack:List<&2, Frame> -> @root:Maybe<&2, 0x729eecea86ea5a2cdba3a2856a313bca/json/value.Json> -> @v:0x729eecea86ea5a2cdba3a2856a313bca/json/value.Json -> @bad:Bool -> P

a finished value lands in the innermost open frame, or becomes the root

def close_arr source · line 41 · raw

@stack:List<&2, Frame> -> @root:Maybe<&2, 0x729eecea86ea5a2cdba3a2856a313bca/json/value.Json> -> @bad:Bool -> P

a ]: the innermost frame must be an array

def close_obj source · line 49 · raw

@stack:List<&2, Frame> -> @root:Maybe<&2, 0x729eecea86ea5a2cdba3a2856a313bca/json/value.Json> -> @bad:Bool -> P

a }: the innermost frame must be an object with no key waiting

def step source · line 57 · raw

@tok:0x729eecea86ea5a2cdba3a2856a313bca/json/lex.Tok -> @st:P -> P

one token

def run source · line 86 · raw

@toks:List<&2, 0x729eecea86ea5a2cdba3a2856a313bca/json/lex.Tok> -> @st:P -> P

every token, in order

def result source · line 94 · raw

@bad:Bool -> @stack:List<&2, Frame> -> @root:Maybe<&2, 0x729eecea86ea5a2cdba3a2856a313bca/json/value.Json> -> Maybe<&2, 0x729eecea86ea5a2cdba3a2856a313bca/json/value.Json>

the root, when nothing went wrong and nothing stayed open

def finish source · line 102 · raw

@st:P -> Maybe<&2, 0x729eecea86ea5a2cdba3a2856a313bca/json/value.Json>

the value once the tokens are over

def parse source · line 107 · raw

@s:String -> Maybe<&2, 0x729eecea86ea5a2cdba3a2856a313bca/json/value.Json>

a text as a value, or None when it is not JSON