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Copy pathLexer.java
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354 lines (328 loc) · 10.1 KB
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package com.ghc.stringparser;
import java.util.ArrayList;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import com.ghc.stringparser.datatype.FloatingPoint;
import com.ghc.stringparser.token.Token;
import com.ghc.stringparser.token.TokenArgument;
import com.ghc.stringparser.token.TokenAssignment;
import com.ghc.stringparser.token.TokenConstant;
import com.ghc.stringparser.token.TokenFunction;
import com.ghc.stringparser.token.TokenGroupEnd;
import com.ghc.stringparser.token.TokenGroupStart;
import com.ghc.stringparser.token.TokenIdentifier;
import com.ghc.stringparser.token.TokenOperator;
import com.ghc.stringparser.token.TokenType;
import com.ghc.stringparser.token.TokenUnary;
public class Lexer {
// Maximum length of operator, ex: <=
private static final int MAX_OPERATOR_LENGTH = 2;
// Maximum length of constant, ex: 20140
private static final int MAX_CONSTANT_LENGTH = 5;
// Maximum length of fraction, ex: 20140.524
private static final int MAX_FRACTION_LENGTH = 3;
// Maximum length of function's name, ex: min
private static final int MAX_FUNCTION_LENGTH = 5;
// Maximum length of identifier's name, ex: x
private static final int MAX_IDENTIFIER_LENGTH = 1;
// Floating point device offset
public static final int FLOATING_POINT_DEVICE_OFFSET = 10;
private int identifierCount = 0;
private Pattern getPattern(String regex) {
return Pattern.compile(regex);
}
public int getIdentifierCount() {
return identifierCount;
}
public List<Token> parse(String input) {
List<Token> tokens = new ArrayList<Token>();
if (input == null || input.length() == 0) {
return tokens;
}
char[] array = getArray(input);
int length = array.length;
for (int i = 0; i < length; i++) {
Token token = getToken(array, i, tokens);
if (token != null) {
tokens.add(token);
i = token.getEnd();
}
}
return tokens;
}
private char[] getArray(String input) {
return input.toCharArray();
}
private Token getToken(char[] input, int start, List<Token> tokens) {
Token token = null;
for (TokenType type : TokenType.values()) {
switch (type) {
case GroupStart:
token = getTokenGroupStart(input, start);
break;
case GroupEnd:
token = getTokenGroupEnd(input, start);
break;
case Constant:
token = getTokenConstant(input, start);
break;
case Argument:
token = getTokenArgument(input, start);
break;
case Assignment:
token = getTokenAssignment(input, start);
break;
default:
break;
}
if (token != null) {
break;
}
}
// Check unary & operator
if (token == null) {
if (isTokenUnary(input, start)) {
// Check previous token
if (tokens.isEmpty()) {
token = createTokenUnary(start);
} else {
Token previous = tokens.get(tokens.size() - 1);
if (previous.getType() == TokenType.Operator
|| previous.getType() == TokenType.GroupStart
|| previous.getType() == TokenType.Unary
|| previous.getType() == TokenType.Assignment
|| previous.getType() == TokenType.Argument) {
token = createTokenUnary(start);
}
}
}
if (token == null) {
token = getTokenOperator(input, start);
}
}
// Check function & identifier
if (token == null) {
token = getTokenFunction(input, start);
if (token == null) {
token = getTokenIdentifier(input, start);
if (token != null) {
identifierCount++;
}
}
}
return token;
}
private Token getTokenGroupStart(char[] input, int start) {
TokenGroupStart token = null;
if (input[start] == '(') {
token = new TokenGroupStart();
token.setOriginal(input[start]);
token.setStart(start);
token.setEnd(start);
}
return token;
}
private Token getTokenGroupEnd(char[] input, int start) {
TokenGroupEnd token = null;
if (input[start] == ')') {
token = new TokenGroupEnd();
token.setOriginal(input[start]);
token.setStart(start);
token.setEnd(start);
}
return token;
}
private Token getTokenOperator(char[] input, int start) {
TokenOperator token = null;
Pattern pattern = getPattern("^[\\+\\*\\-\\/]");
Matcher matcher = pattern.matcher(String.valueOf(input[start]));
if (matcher.find()) {
String subString = getSubString(input, start, MAX_OPERATOR_LENGTH);
matcher = pattern.matcher(subString);
if (matcher.find()) {
String original = matcher.group();
token = new TokenOperator();
token.setOriginal(original);
token.setStart(start);
token.setEnd(start + original.length() - 1);
}
}
return token;
}
private Token getTokenConstant(char[] input, int start) {
TokenConstant token = null;
Pattern pattern = getPattern("^[0-9]");
Matcher matcher = pattern.matcher(String.valueOf(input[start]));
if (matcher.find()) {
pattern = getPattern("^[0-9]*\\.?[0-9]+");
String subString = getSubString(input, start, MAX_CONSTANT_LENGTH
+ 1 + MAX_FRACTION_LENGTH);
matcher = pattern.matcher(subString);
if (matcher.find()) {
String original = matcher.group();
token = new TokenConstant();
token.setOriginal(original);
token.setStart(start);
token.setEnd(start + original.length() - 1);
int dot = original.indexOf(".");
int value = 0;
int fraction = 0;
int devide = 1;
if (dot == -1) {
value = Integer.parseInt(original);
} else {
value = Integer.parseInt(original.substring(0, dot));
if (dot < original.length() - 1) {
String sFraction = original.substring(dot + 1);
fraction = Integer.parseInt(sFraction);
for (int i = 0; i < sFraction.length(); i++) {
devide = devide * FLOATING_POINT_DEVICE_OFFSET;
}
}
}
FloatingPoint floatingPoint = new FloatingPoint();
floatingPoint.setValue(value);
floatingPoint.setFraction(fraction);
floatingPoint.setDevide(devide);
token.setValue(floatingPoint);
}
}
return token;
}
private Token getTokenFunction(char[] input, int start) {
TokenFunction token = null;
Pattern pattern = getPattern("^[a-zA-Z]");
Matcher matcher = pattern.matcher(String.valueOf(input[start]));
if (matcher.find()) {
pattern = getPattern("^(min|max)");
String subString = getSubString(input, start, MAX_FUNCTION_LENGTH);
matcher = pattern.matcher(subString);
if (matcher.find()) {
String original = matcher.group();
token = new TokenFunction();
token.setOriginal(original);
token.setStart(start);
token.setEnd(start + original.length() - 1);
}
}
return token;
}
private Token getTokenArgument(char[] input, int start) {
TokenArgument token = null;
if (input[start] == ',') {
token = new TokenArgument();
token.setOriginal(input[start]);
token.setStart(start);
token.setEnd(start);
}
return token;
}
private Token getTokenIdentifier(char[] input, int start) {
TokenIdentifier token = null;
Pattern pattern = getPattern("^[a-zA-Z]");
Matcher matcher = pattern.matcher(String.valueOf(input[start]));
if (matcher.find()) {
pattern = getPattern("^[a-zA-Z]+");
String subString = getSubString(input, start, MAX_IDENTIFIER_LENGTH);
matcher = pattern.matcher(subString);
if (matcher.find()) {
String original = matcher.group();
token = new TokenIdentifier();
token.setOriginal(original);
token.setStart(start);
token.setEnd(start + original.length() - 1);
}
}
return token;
}
private Token getTokenAssignment(char[] input, int start) {
TokenAssignment token = null;
if (input[start] == '=') {
token = new TokenAssignment();
token.setOriginal(input[start]);
token.setStart(start);
token.setEnd(start);
}
return token;
}
private boolean isTokenUnary(char[] input, int start) {
if (input[start] == '-') {
return true;
}
return false;
}
private Token createTokenUnary(int start) {
TokenUnary token = new TokenUnary();
token.setOriginal('-');
token.setStart(start);
token.setEnd(start);
return token;
}
private String getSubString(char[] input, int start, int maxLength) {
StringBuilder sb = new StringBuilder();
int end = start + maxLength;
for (int i = start; i < input.length && i < end; i++) {
sb.append(input[i]);
}
return sb.toString();
}
public void printTokens(List<Token> tokens, StringBuilder sb) {
for (Token token : tokens) {
String original = "";
int value = 0;
int fraction = 0;
int devide = 1;
switch (token.getType()) {
case GroupStart:
original = String.valueOf(((TokenGroupStart) token)
.getOriginal());
break;
case GroupEnd:
original = String
.valueOf(((TokenGroupEnd) token).getOriginal());
break;
case Operator:
original = ((TokenOperator) token).getOriginal();
break;
case Constant:
original = ((TokenConstant) token).getOriginal();
value = ((TokenConstant) token).getValue().getValue();
fraction = ((TokenConstant) token).getValue().getFraction();
devide = ((TokenConstant) token).getValue().getDevide();
break;
case Function:
original = ((TokenFunction) token).getOriginal();
break;
case Argument:
original = String
.valueOf(((TokenArgument) token).getOriginal());
break;
case Identifier:
original = ((TokenIdentifier) token).getOriginal();
break;
case Assignment:
original = String.valueOf(((TokenAssignment) token)
.getOriginal());
break;
case Unary:
original = String.valueOf(((TokenUnary) token).getOriginal());
break;
default:
break;
}
if (token.getType() == TokenType.Constant) {
sb.append(String
.format("Original %s, Type %s, Value %d, Fraction %d, Devide %d, start %d, end %d \n",
original, token.getType().name(), value,
fraction, devide, token.getStart(),
token.getEnd()));
} else {
sb.append(String.format(
"Original %s, Type %s, start %d, end %d \n", original,
token.getType().name(), token.getStart(),
token.getEnd()));
}
}
}
}