Changed formatting to match Markus Triska's as much as I can tell
This commit is contained in:
216
src/lib/json.pl
216
src/lib/json.pl
@@ -47,7 +47,7 @@
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:- use_module(library(lists)).
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:- use_module(library(reif)).
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/* The DCGs are written to match the McKeeman Form presented on the right side of https://www.json.org/json-en.html
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/* The DCGs are written to match the McKeeman form presented on the right side of https://www.json.org/json-en.html
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almost perfectly. Note that the McKeeman form conflicts some with the pictures on the left side. */
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json_chars(Internal) --> json_element(Internal).
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@@ -55,13 +55,13 @@ json_chars(Internal) --> json_element(Internal).
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different types of values based on their principal functor. The principal functors match the types defined in
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the JSON Schema spec here: https://json-schema.org/draft/2020-12/json-schema-validation.html#rfc.section.6.1.1
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Down the line we'll incorporate more JSON Schema support, but this is it for now. */
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json_value(object(Assoc)) --> json_object(Assoc).
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json_value(array(List)) --> json_array(List).
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json_value(string(Chars)) --> json_string(Chars).
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json_value(number(Number)) --> json_number(Number).
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json_value(boolean(true)) --> "true".
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json_value(boolean(false)) --> "false".
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json_value(null) --> "null".
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json_value(object(Assoc)) --> json_object(Assoc).
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json_value(array(List)) --> json_array(List).
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json_value(string(Chars)) --> json_string(Chars).
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json_value(number(Number)) --> json_number(Number).
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json_value(boolean(true)) --> "true".
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json_value(boolean(false)) --> "false".
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json_value(null) --> "null".
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/* Read Bob Kowalski's "Algorithm = Logic + Control":
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https://www.doc.ic.ac.uk/~rak/papers/algorithm%20=%20logic%20+%20control.pdf
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@@ -73,38 +73,36 @@ json_value(null) --> "null".
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Maybe at some point in the future we'll have a library that takes a pure logic character parsing/generating DCG
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and 'injects' control strategy into it. We aren't there yet... */
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json_object(EmptyAssoc) --> {empty_assoc(EmptyAssoc)}, "{", json_ws, "}".
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json_object(Assoc) -->
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{
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nonvar(Assoc) ->
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\+ empty_assoc(Assoc),
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assoc_to_list(Assoc, [Pair|Pairs])
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; true
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},
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"{",
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json_members([Pair|Pairs]),
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"}",
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{
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var(Assoc) ->
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list_to_assoc([Pair|Pairs], Assoc)
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; true
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}.
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json_object(Assoc) -->
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{ ( nonvar(Assoc) ->
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\+ empty_assoc(Assoc),
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assoc_to_list(Assoc, [Pair|Pairs])
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; true
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) },
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"{",
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json_members([Pair|Pairs]),
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"}",
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{ ( var(Assoc) ->
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list_to_assoc([Pair|Pairs], Assoc)
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; true
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) }.
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json_members([Key-Value]) --> json_member(Key, Value).
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json_members([Key-Value]) --> json_member(Key, Value).
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json_members([Key-Value | Pairs]) --> json_member(Key, Value), ",", json_members(Pairs).
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json_member(Key, Value) --> json_ws, json_string(Key), json_ws, ":", json_element(Value).
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json_array([]) --> "[", json_ws, "]".
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json_array([]) --> "[", json_ws, "]".
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json_array([Value|Values]) --> "[", json_elements([Value|Values]), "]".
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json_elements([Value]) --> json_element(Value).
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json_elements([Value]) --> json_element(Value).
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json_elements([Value|Values]) --> json_element(Value), ",", json_elements(Values).
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json_element(Value) --> json_ws, json_value(Value), json_ws.
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json_string(Chars) --> "\"", json_characters(Chars), "\"".
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json_characters("") --> "".
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json_characters("") --> "".
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json_characters([Char|Chars]) --> json_character(Char), json_characters(Chars).
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/* A directly printable character is defined by the JSON spec as a character between 0020 and 10FFFF except the
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@@ -114,114 +112,100 @@ json_characters([Char|Chars]) --> json_character(Char), json_characters(Chars).
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If we moved the block containing `char_code/2` up before `[PrintChar]`, we would still be able to generate JSON,
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but attempting to parse JSON would cause an instantiation error. */
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escape_map([
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'"' - '"',
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('\\') - ('\\'),
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('/') - ('/'),
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'\b' - 'b',
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'\f' - 'f',
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'\n' - 'n',
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'\r' - 'r',
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'\t' - 't'
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]).
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'"' - '"',
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('\\') - ('\\'),
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('/') - ('/'),
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'\b' - 'b',
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'\f' - 'f',
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'\n' - 'n',
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'\r' - 'r',
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'\t' - 't' ]).
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json_character(PrintChar) -->
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[PrintChar],
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{
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escape_map(EscapeMap),
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\+ member(PrintChar-_, EscapeMap),
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char_code(PrintChar, PrintCharCode),
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PrintCharCode in 32..1114111 /* 20.10FFFF */
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}.
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json_character(PrintChar) -->
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[PrintChar],
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{ escape_map(EscapeMap),
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\+ member(PrintChar-_, EscapeMap),
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char_code(PrintChar, PrintCharCode),
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PrintCharCode in 32..1114111 /* 20.10FFFF */ }.
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json_character(EscapeChar) --> "\\", json_escape(EscapeChar).
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json_escape(EscapeChar) -->
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[PrintChar],
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{
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escape_map(EscapeMap),
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member(EscapeChar-PrintChar, EscapeMap)
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}.
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[PrintChar],
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{ escape_map(EscapeMap),
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member(EscapeChar-PrintChar, EscapeMap) }.
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json_escape(EscapeChar) -->
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"u",
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{ /* Logic: Define the domain of the escape character as well as the relationship between the escape character
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"u",
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/* Logic: Define the domain of the escape character as well as the relationship between the escape character
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and the four hexes */
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[H1, H2, H3, H4] ins 0..15,
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EscapeCharCode in 0..65535,
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EscapeCharCode #= H1 * 16^3 + H2 * 16^2 + H3 * 16 + H4
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},
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{ /* Control: Get the code of the escape character if we can. Otherwise we'll end up backtracking over 65,536
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possible hex values.
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Logic: Only the first 32 Unicode characters not escaped in the escape map are eligible for \u-escaping
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when generating. However, we want to be able to parse any of the 65,536 \u-escaped values when parsing. */
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nonvar(EscapeChar) ->
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char_code(EscapeChar, EscapeCharCode),
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EscapeCharCode in 0..31,
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escape_map(EscapeMap),
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\+ member(EscapeChar-_, EscapeMap)
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; true
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},
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json_hex(H1),
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json_hex(H2),
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json_hex(H3),
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json_hex(H4),
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{ /* Control + Logic: Get the escape character atom from the character code computed from the hexes. */
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var(EscapeChar) ->
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char_code(EscapeChar, EscapeCharCode)
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; true
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}.
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{ [H1, H2, H3, H4] ins 0..15,
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EscapeCharCode in 0..65535,
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EscapeCharCode #= H1 * 16^3 + H2 * 16^2 + H3 * 16 + H4,
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/* Control: Get the code of the escape character if we can. Otherwise we'll end up backtracking over 65,536
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possible hex values.
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Logic: Only the first 32 Unicode characters not escaped in the escape map are eligible for \u-escaping
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when generating. However, we want to be able to parse any of the 65,536 \u-escaped values when parsing. */
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( nonvar(EscapeChar) ->
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char_code(EscapeChar, EscapeCharCode),
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EscapeCharCode in 0..31,
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escape_map(EscapeMap),
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\+ member(EscapeChar-_, EscapeMap)
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; true
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)
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},
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json_hex(H1),
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json_hex(H2),
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json_hex(H3),
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json_hex(H4),
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/* Control + Logic: Get the escape character atom from the character code computed from the hexes. */
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{ ( var(EscapeChar) ->
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char_code(EscapeChar, EscapeCharCode)
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; true
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) }.
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json_hex(Digit) --> json_digit(Digit).
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json_hex(10) --> "a".
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json_hex(11) --> "b".
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json_hex(12) --> "c".
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json_hex(13) --> "d".
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json_hex(14) --> "e".
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json_hex(15) --> "f".
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json_hex(10) --> "A".
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json_hex(11) --> "B".
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json_hex(12) --> "C".
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json_hex(13) --> "D".
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json_hex(14) --> "E".
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json_hex(15) --> "F".
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json_hex(10) --> "a".
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json_hex(11) --> "b".
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json_hex(12) --> "c".
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json_hex(13) --> "d".
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json_hex(14) --> "e".
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json_hex(15) --> "f".
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json_hex(10) --> "A".
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json_hex(11) --> "B".
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json_hex(12) --> "C".
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json_hex(13) --> "D".
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json_hex(14) --> "E".
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json_hex(15) --> "F".
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/* Here we are going to write completely different DCGs for parsing and generating, and rely on built-in
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predicates. However, the underlying logic remains the same. */
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json_number(Number) -->
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{
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nonvar(Number) ->
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number_chars(Number, NumberChars)
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; false
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},
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{ ( nonvar(Number) ->
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number_chars(Number, NumberChars)
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; false
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) },
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NumberChars.
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json_number(Number) -->
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{
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var(Number)
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},
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{ var(Number) },
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json_sign_noplus(Sign),
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json_integer(Integer),
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json_fraction(Fraction),
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json_exponent(Exponent),
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{
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Number is Sign * (Integer + Fraction) * 10.0 ^ Exponent
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}.
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{ Number is Sign * (Integer + Fraction) * 10.0 ^ Exponent }.
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json_integer(Digit) --> json_digit(Digit).
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json_integer(Digit) --> json_digit(Digit).
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json_integer(TotalValue) -->
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json_onenine(FirstDigit),
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json_digits(RemainingValue, Power),
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{
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TotalValue #= FirstDigit * 10 ^ (Power + 1) + RemainingValue
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}.
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{ TotalValue #= FirstDigit * 10 ^ (Power + 1) + RemainingValue }.
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json_digits(Digit, 0) --> json_digit(Digit).
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json_digits(Digit, 0) --> json_digit(Digit).
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json_digits(Value, Power) -->
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json_digit(FirstDigit),
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json_digits(RemainingValue, NextPower),
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{
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Power #= NextPower + 1,
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Value #= FirstDigit * 10^Power + RemainingValue
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}.
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{ Power #= NextPower + 1,
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Value #= FirstDigit * 10^Power + RemainingValue }.
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json_digit(0) --> "0".
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json_digit(0) --> "0".
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json_digit(Digit) --> json_onenine(Digit).
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json_onenine(1) --> "1".
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@@ -234,31 +218,27 @@ json_onenine(7) --> "7".
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json_onenine(8) --> "8".
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json_onenine(9) --> "9".
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json_fraction(0) --> "".
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json_fraction(0) --> "".
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json_fraction(Fraction) -->
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".",
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json_digits(Value, Power),
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{
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Fraction is Value / 10 ^ (Power + 1)
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}.
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{ Fraction is Value / 10 ^ (Power + 1) }.
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json_exponent(0) --> "".
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json_exponent(0) --> "".
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json_exponent(Exponent) -->
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json_exponent_signifier,
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json_sign(Sign),
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json_digits(Value, _),
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{
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Exponent #= Sign * Value
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}.
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{ Exponent #= Sign * Value }.
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json_exponent_signifier --> "E".
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json_exponent_signifier --> "e".
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json_sign_noplus(1) --> "".
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json_sign_noplus(1) --> "".
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json_sign_noplus(-1) --> "-".
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json_sign(Sign) --> json_sign_noplus(Sign).
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json_sign(1) --> "+".
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json_sign(1) --> "+".
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json_ws --> "".
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json_ws --> " ", json_ws.
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