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| import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; import java.util.regex.Matcher; import java.util.regex.Pattern;
public class JSONUtils {
public static Map<String, Object> parseObjectText(String text) throws Exception { Object o = parseText(text); if (!(o instanceof Map)) { throw new Exception(); } return (Map<String, Object>) o; }
public static List<Object> parseArrayText(String text) throws Exception { Object o = parseText(text); if (!(o instanceof List)) { throw new Exception(); } return (List<Object>) o; }
public static Object parseText(String text) throws Exception { return parseTokens(parseTextToTokens(text), 0).data; }
public static String formatText(String text) throws Exception { return formatTokens(parseTextToTokens(text)); }
private static Token getFirstToken(String text, TokenType type) { Matcher matcher = type.pattern.matcher(text); if (!matcher.find()) { return null; } return new Token(type, matcher.group(0)); }
private static String transString(String text) { StringBuilder val = new StringBuilder(); for (int i = 1; i < text.length() - 1; i++) { if (text.charAt(i) != '\\') { val.append(text.charAt(i)); } else { switch (text.charAt(i + 1)) { case 'n': val.append('\n'); break; case 't': val.append('\t'); break; default: val.append(text.charAt(i + 1)); break; } i++; } } return val.toString(); }
private static TokensParseResult parseTokens(List<Token> tokens, int index) throws Exception { switch (tokens.get(index).type) { case OBJECT_OPEN: { index++; Map<String, Object> data = new HashMap<>(); while (tokens.get(index).type != TokenType.OBJECT_CLOSE) { if (tokens.get(index).type == TokenType.STRING && tokens.get(index + 1).type == TokenType.COLON) { TokensParseResult item = parseTokens(tokens, index + 2); data.put(transString(tokens.get(index).value), item.data); index = item.nextIndex; if (tokens.get(index).type == TokenType.SPLIT) { index++; } } else { throw new Exception(); } } return new TokensParseResult(data, index + 1); } case ARRAY_OPEN: { index++; List<Object> data = new ArrayList<>(); while (tokens.get(index).type != TokenType.ARRAY_CLOSE) { TokensParseResult item = parseTokens(tokens, index); data.add(item.data); index = item.nextIndex; if (tokens.get(index).type == TokenType.SPLIT) { index++; } } return new TokensParseResult(data, index + 1);
} case STRING: return new TokensParseResult(transString(tokens.get(index).value), index + 1); case NUMBER: return new TokensParseResult(Double.parseDouble(tokens.get(index).value), index + 1); case BOOLEAN: return new TokensParseResult(Boolean.parseBoolean(tokens.get(index).value), index + 1); case NULL: return new TokensParseResult(null, index + 1); default: throw new Exception(); } }
private static String enter(int depth) { StringBuilder val = new StringBuilder("\n"); for (int i = 0; i < depth; i++) { val.append(" "); } return val.toString(); }
private static String formatTokens(List<Token> tokens) { StringBuilder format = new StringBuilder(); int depth = 0; for (Token token : tokens) { if (token.type == TokenType.OBJECT_CLOSE || token.type == TokenType.ARRAY_CLOSE) { format.append(enter(--depth)); } format.append(token.value); if (token.type == TokenType.OBJECT_OPEN || token.type == TokenType.ARRAY_OPEN) { format.append(enter(++depth)); } if (token.type == TokenType.SPLIT) { format.append(enter(depth)); } } return format.toString(); }
private static List<Token> parseTextToTokens(String text) throws Exception { List<Token> tokens = new ArrayList<>(); while (!text.isEmpty()) { Token token = null; for (TokenType type : TokenType.values()) { token = getFirstToken(text, type); if (token != null) { break; } } if (token == null) { throw new Exception(); } text = text.substring(token.value.length()); if (token.type == TokenType.SPACE) { continue; } tokens.add(token); } return tokens; }
private static class Token { private TokenType type; private String value;
private Token(TokenType type, String value) { this.type = type; this.value = value; } }
private static class TokensParseResult { private Object data; private int nextIndex;
TokensParseResult(Object data, int nextIndex) { this.data = data; this.nextIndex = nextIndex; } }
private enum TokenType { STRING("^(\"([^\"\\\\]|\\\\.)*\")"), NUMBER("^(-?\\d+(\\.\\d+)?)"), BOOLEAN("^(true|false)"), NULL("^(null)"), OBJECT_OPEN("^(\\{)"), OBJECT_CLOSE("^(\\})"), ARRAY_OPEN("^(\\[)"), ARRAY_CLOSE("^(\\])"), COLON("^(\\:)"), SPLIT("^(\\,)"), SPACE("^([\\s\\r\\n]+)"); private Pattern pattern;
TokenType(String reg) { this.pattern = Pattern.compile(reg); } } }
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