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comparison core/src/luan/modules/parsers/Json.java @ 720:bdd766df1c17

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add json parser
author Franklin Schmidt <fschmidt@gmail.com>
date Mon, 30 May 2016 21:27:17 -0600
parents
children c29d11d675fd
comparison
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719:53fc65ffa65f 720:bdd766df1c17
1 package luan.modules.parsers;
2
3 import java.util.List;
4 import java.util.ArrayList;
5 import java.util.Map;
6 import java.util.LinkedHashMap;
7 import luan.LuanTable;
8
9
10 public final class Json {
11
12 public static Object parse(String text) throws ParseException {
13 return new Json(text).parse();
14 }
15
16 private final Parser parser;
17
18 private Json(String text) {
19 this.parser = new Parser(text);
20 }
21
22 private ParseException exception(String msg) {
23 return new ParseException(parser,msg);
24 }
25
26 private Object parse() throws ParseException {
27 spaces();
28 Object value = value();
29 spaces();
30 if( !parser.endOfInput() )
31 throw exception("unexpected text");
32 return value;
33 }
34
35 private Object value() throws ParseException {
36 if( parser.match("null") )
37 return null;
38 if( parser.match("true") )
39 return Boolean.TRUE;
40 if( parser.match("false") )
41 return Boolean.FALSE;
42 String s = string();
43 if( s != null )
44 return s;
45 Number n = number();
46 if( n != null )
47 return n;
48 LuanTable a = array();
49 if( a != null )
50 return a;
51 LuanTable o = object();
52 if( o != null )
53 return o;
54 throw exception("invalid value");
55 }
56
57 private String string() throws ParseException {
58 parser.begin();
59 if( !parser.match('"') )
60 return parser.failure(null);
61 StringBuilder sb = new StringBuilder();
62 while( parser.anyChar() ) {
63 char c = parser.lastChar();
64 switch(c) {
65 case '"':
66 return parser.success(sb.toString());
67 case '\\':
68 if( parser.anyChar() ) {
69 c = parser.lastChar();
70 switch(c) {
71 case '"':
72 case '\\':
73 case '/':
74 sb.append(c);
75 continue;
76 case 'b':
77 sb.append('\b');
78 continue;
79 case 'f':
80 sb.append('\f');
81 continue;
82 case 'n':
83 sb.append('\n');
84 continue;
85 case 'r':
86 sb.append('\r');
87 continue;
88 case 't':
89 sb.append('\t');
90 continue;
91 case 'u':
92 int n = 0;
93 for( int i=0; i<4; i++ ) {
94 int d;
95 if( parser.inCharRange('0','9') ) {
96 d = parser.lastChar() - '0';
97 } else if( parser.inCharRange('a','f') ) {
98 d = parser.lastChar() - 'a' + 10;
99 } else if( parser.inCharRange('A','F') ) {
100 d = parser.lastChar() - 'A' + 10;
101 } else {
102 throw exception("invalid hex digit");
103 }
104 n = 16*n + d;
105 }
106 sb.append((char)n);
107 continue;
108 }
109 }
110 throw exception("invalid escape char");
111 default:
112 sb.append(c);
113 }
114 }
115 parser.failure();
116 throw exception("unclosed string");
117 }
118
119 private Number number() {
120 int start = parser.begin();
121 parser.match('-');
122 if( !parser.match('0') ) {
123 if( !parser.inCharRange('1','9') )
124 return parser.failure(null);
125 while( parser.inCharRange('0','9') );
126 }
127 if( parser.match('.') ) {
128 if( !parser.inCharRange('0','9') )
129 return parser.failure(null);
130 while( parser.inCharRange('0','9') );
131 }
132 if( parser.anyOf("eE") ) {
133 parser.anyOf("+-");
134 if( !parser.inCharRange('0','9') )
135 return parser.failure(null);
136 while( parser.inCharRange('0','9') );
137 }
138 String s = parser.textFrom(start);
139 return parser.success(Double.valueOf(s));
140 }
141
142 private LuanTable array() throws ParseException {
143 parser.begin();
144 if( !parser.match('[') )
145 return parser.failure(null);
146 spaces();
147 if( parser.match(']') )
148 return parser.success(new LuanTable());
149 List list = new ArrayList();
150 list.add( value() );
151 spaces();
152 while( parser.match(',') ) {
153 spaces();
154 list.add( value() );
155 spaces();
156 }
157 if( parser.match(']') )
158 return parser.success(new LuanTable(list));
159 if( parser.endOfInput() ) {
160 parser.failure();
161 throw exception("unclosed array");
162 }
163 throw exception("unexpected text in array");
164 }
165
166 private LuanTable object() throws ParseException {
167 parser.begin();
168 if( !parser.match('{') )
169 return parser.failure(null);
170 spaces();
171 if( parser.match('}') )
172 return parser.success(new LuanTable());
173 Map map = new LinkedHashMap();
174 addEntry(map);
175 while( parser.match(',') ) {
176 spaces();
177 addEntry(map);
178 }
179 if( parser.match('}') )
180 return parser.success(new LuanTable(map));
181 if( parser.endOfInput() ) {
182 parser.failure();
183 throw exception("unclosed object");
184 }
185 throw exception("unexpected text in object");
186 }
187
188 private void addEntry(Map map) throws ParseException {
189 String key = string();
190 if( key==null )
191 throw exception("invalid object key");
192 spaces();
193 if( !parser.match(':') )
194 throw exception("':' expected");
195 spaces();
196 Object value = value();
197 spaces();
198 map.put(key,value);
199 }
200
201 private void spaces() {
202 while( parser.anyOf(" \t\r\n") );
203 }
204 }