1	# ezjson: JSON for Bend 2, with a parser, a printer and a pull cursor
2	#
3	# `parse` reads text into Maybe Json. `print` writes compact text and
4	# `pretty` indented text. `cursor` reads one event at a time. Build null,
5	# booleans, numbers, strings, arrays, and objects; read them with get, at, and
6	# as_bool, as_str, as_num, as_u32, as_f32; has and len tell a missing key or
7	# index from a null.
8	import Base
9	import ./src/value.bend as Value
10	import ./src/parse.bend as Parse
11	import ./src/print.bend as Print
12	import ./src/pull.bend as Pull
13	
14	# a text as a value, or None when it is not JSON
15	def parse(txt: String) -> Maybe<&2, Value.Json>:
16	  Parse.parse(txt)
17	
18	# a value as compact JSON
19	def print(val: Value.Json) -> String:
20	  Print.print(val)
21	
22	# a value as JSON indented two spaces a level, one element or member a line,
23	# with no newline at the end
24	def pretty(val: Value.Json) -> String:
25	  Print.pretty(val)
26	
27	# null
28	def null() -> Value.Json:
29	  Value.null()
30	
31	# a boolean
32	def bool(flag: Bool) -> Value.Json:
33	  Value.bool(flag)
34	
35	# a string
36	def str(txt: String) -> Value.Json:
37	  Value.str(txt)
38	
39	# a JSON number from its text, or null when that text is not one
40	def num(raw: String) -> Value.Json:
41	  Value.num(raw)
42	
43	# an object from pairs
44	def obj(pairs: List<&1, String & Value.Json>) -> Value.Json:
45	  Value.obj(pairs)
46	
47	# an array from a list
48	def arr(items: List<&2, Value.Json>) -> Value.Json:
49	  Value.arr(items)
50	
51	# an object's value at a key; JNull when it is not an object or has no such
52	# key
53	def get(val: Value.Json, key: String) -> Value.Json:
54	  Value.get(val, key)
55	
56	# an array's item at an index; JNull when it is not an array or has none
57	def at(val: Value.Json, idx: U32) -> Value.Json:
58	  Value.at(val, idx)
59	
60	# whether an object has a key; false when the value is not an object. Tells
61	# a missing key from a key whose value is null, which `get` does not
62	def has(val: Value.Json, key: String) -> Bool:
63	  Value.has(val, key)
64	
65	# how many elements an array, or members an object, has; 0 for anything else
66	def len(val: Value.Json) -> U32:
67	  Value.len(val)
68	
69	# a boolean, or none when the value is not one
70	def as_bool(val: Value.Json) -> Maybe<&2, Bool>:
71	  Value.as_bool(val)
72	
73	# a string, or none when the value is not one
74	def as_str(val: Value.Json) -> Maybe<&2, String>:
75	  Value.as_str(val)
76	
77	# a number's text, or none when the value is not a number
78	def as_num(val: Value.Json) -> Maybe<&2, String>:
79	  Value.as_num(val)
80	
81	# a number as a U32, or none when it is not one or does not fit
82	def as_u32(val: Value.Json) -> Maybe<&2, U32>:
83	  Value.as_u32(val)
84	
85	# a number as an F32, or none when it is not one or does not fit
86	def as_f32(val: Value.Json) -> Maybe<&2, F32>:
87	  Value.as_f32(val)
88	
89	# a cursor at the start of a JSON text. It holds the unread suffix of that
90	# text. A span event keeps its own suffix, so it stays valid after `next`
91	# moves the cursor, and it is gone when the event is dropped
92	def cursor(src: String) -> Pull.Cur:
93	  Pull.cursor(src)
94	
95	# the next event. Commas and colons are not events. After the root value,
96	# the next call is the end, or an error if another value follows
97	def next(cur: Pull.Cur) -> (Pull.Ev & Pull.Cur):
98	  Pull.next(cur)
99	
100	# drop the next value, scalar or container, without building it
101	def skip(cur: Pull.Cur) -> Pull.Cur:
102	  Pull.skip(cur)
103	
104	# the text of a string, key, or number event, copying a span. None otherwise
105	def text(ev: Pull.Ev) -> Maybe<&2, String>:
106	  Pull.text(ev)