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; items lists an array's elements, and is_arr and is_obj
8	# tell the containers apart.
9	import Base
10	import ./src/value.bend as Value
11	import ./src/parse.bend as Parse
12	import ./src/print.bend as Print
13	import ./src/pull.bend as Pull
14	
15	# a text as a value, or None when it is not JSON
16	def parse(txt: String) -> Maybe<&2, Value.Json>:
17	  Parse.parse(txt)
18	
19	# a value as compact JSON
20	def print(val: Value.Json) -> String:
21	  Print.print(val)
22	
23	# a value as JSON indented two spaces a level, one element or member a line,
24	# with no newline at the end
25	def pretty(val: Value.Json) -> String:
26	  Print.pretty(val)
27	
28	# null
29	def null() -> Value.Json:
30	  Value.null()
31	
32	# a boolean
33	def bool(flag: Bool) -> Value.Json:
34	  Value.bool(flag)
35	
36	# a string
37	def str(txt: String) -> Value.Json:
38	  Value.str(txt)
39	
40	# a JSON number from its text, or null when that text is not one
41	def num(raw: String) -> Value.Json:
42	  Value.num(raw)
43	
44	# an object from pairs
45	def obj(pairs: List<&1, String & Value.Json>) -> Value.Json:
46	  Value.obj(pairs)
47	
48	# an array from a list
49	def arr(items: List<&2, Value.Json>) -> Value.Json:
50	  Value.arr(items)
51	
52	# an object's value at a key; JNull when it is not an object or has no such
53	# key
54	def get(val: Value.Json, key: String) -> Value.Json:
55	  Value.get(val, key)
56	
57	# an array's item at an index; JNull when it is not an array or has none
58	def at(val: Value.Json, idx: U32) -> Value.Json:
59	  Value.at(val, idx)
60	
61	# whether an object has a key; false when the value is not an object. Tells
62	# a missing key from a key whose value is null, which `get` does not
63	def has(val: Value.Json, key: String) -> Bool:
64	  Value.has(val, key)
65	
66	# how many elements an array, or members an object, has; 0 for anything else
67	def len(val: Value.Json) -> U32:
68	  Value.len(val)
69	
70	# an array's elements, in order; [] when the value is not an array. One
71	# walk of the array, where a loop over `at` walks it again for every index
72	def items(val: Value.Json) -> List<&2, Value.Json>:
73	  Value.items(val)
74	
75	# whether a value is an array
76	def is_arr(val: Value.Json) -> Bool:
77	  Value.is_arr(val)
78	
79	# whether a value is an object
80	def is_obj(val: Value.Json) -> Bool:
81	  Value.is_obj(val)
82	
83	# a boolean, or none when the value is not one
84	def as_bool(val: Value.Json) -> Maybe<&2, Bool>:
85	  Value.as_bool(val)
86	
87	# a string, or none when the value is not one
88	def as_str(val: Value.Json) -> Maybe<&2, String>:
89	  Value.as_str(val)
90	
91	# a number's text, or none when the value is not a number
92	def as_num(val: Value.Json) -> Maybe<&2, String>:
93	  Value.as_num(val)
94	
95	# a number as a U32, or none when it is not one or does not fit
96	def as_u32(val: Value.Json) -> Maybe<&2, U32>:
97	  Value.as_u32(val)
98	
99	# a number as an F32, or none when it is not one or does not fit
100	def as_f32(val: Value.Json) -> Maybe<&2, F32>:
101	  Value.as_f32(val)
102	
103	# a cursor at the start of a JSON text. It holds the unread suffix of that
104	# text. A span event keeps its own suffix, so it stays valid after `next`
105	# moves the cursor, and it is gone when the event is dropped
106	def cursor(src: String) -> Pull.Cur:
107	  Pull.cursor(src)
108	
109	# the next event. Commas and colons are not events. After the root value,
110	# the next call is the end, or an error if another value follows
111	def next(cur: Pull.Cur) -> (Pull.Ev & Pull.Cur):
112	  Pull.next(cur)
113	
114	# drop the next value, scalar or container, without building it
115	def skip(cur: Pull.Cur) -> Pull.Cur:
116	  Pull.skip(cur)
117	
118	# the text of a string, key, or number event, copying a span. None otherwise
119	def text(ev: Pull.Ev) -> Maybe<&2, String>:
120	  Pull.text(ev)