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package compiler.lexer;
import java.text.CharacterIterator;
import java.text.StringCharacterIterator;
public class NumberFloat
{
static enum Type{
Number,Float
}
private StringCharacterIterator iter = null;
private char currentChar;
private String currentToken="";
/**
* @param iter
*/
public NumberFloat(String sourceCode)
{
this.iter = new StringCharacterIterator(sourceCode);
this.currentChar = this.iter.first();
}
public char nextChar()
{
add(this.currentChar);
this.currentChar = iter.next();
return currentChar;
}
public Token parse()
{
// 1
if (this.currentChar == '+' || this.currentChar == '-')
{
this.nextChar();
// 2
if (isDigit())
{
this.nextChar();
// 3
digitClosure();
if (isDone())
{
return new Token(Token.Number, this.currentToken);
}
// 4
else if (isPoint())
{
this.nextChar();
// 5
if (isDigit())
{
this.nextChar();
digitClosure();
if (isDone())
{
return new Token(Token.Float, this.currentToken);
}
}
}
}
}
// 1
else if (isDigit())
{
this.nextChar();
// 3
digitClosure();
if (isDone())
{
return new Token(Token.Number, this.currentToken);
}
// 4
else if (isPoint())
{
this.nextChar();
// 5
if (isDigit())
{
this.nextChar();
digitClosure();
if (isDone())
{
return new Token(Token.Float, this.currentToken);
}
}
}
}
System.out.println("error char at [" + this.currentChar + "].current parsed code:[" + this.currentToken+"]");
return null;
}
private void digitClosure()
{
while (true)
{
if (isDigit())
{
this.nextChar();
continue;
}
else
break;
}
}
private boolean isPoint()
{
return this.currentChar == '.';
}
private boolean isDigit()
{
return Character.isDigit(this.currentChar);
}
private boolean isDone()
{
return this.currentChar == CharacterIterator.DONE;
}
private void add(char c)
{
this.currentToken += c;
}
private void clear()
{
this.currentToken = "";
}
public static void main(String[] args)
{
System.out.println(new NumberFloat("100").parse());
System.out.println(new NumberFloat("+100").parse());
System.out.println(new NumberFloat("-100").parse());
System.out.println(new NumberFloat("100.1").parse());
System.out.println(new NumberFloatV2("100.1.").parse());
// StringCharacterIterator iter = new StringCharacterIterator("100");
// for(char c = iter.first(); c != CharacterIterator.DONE; c = iter.next()) {
// System.out.println(c);
// }
}
}
package compiler.lexer;
import java.text.CharacterIterator;
import java.text.StringCharacterIterator;
/**
*
* 输入:
* 输出:
* 描述: 区别于NumberFloat,这里是使用了DFA的节点编号来实现,这种实现方式的好处是直接按照图来翻译成代码非常方便
* 用法:
*
*/
public class NumberFloatV2
{
static enum Type{
Number,Float
}
private StringCharacterIterator iter = null;
private char currentChar;
private String currentToken="";
private int nextNo4DFA = 1;
private String copySourceCode;
/**
* @param iter
*/
public NumberFloatV2(String sourceCode)
{
this.iter = new StringCharacterIterator(sourceCode);
this.copySourceCode = sourceCode;
}
public char nextChar()
{
add(this.currentChar);
this.currentChar = iter.next();
return currentChar;
}
public Token parse()
{
this.currentChar = iter.first();
// 1
if (this.currentChar == '+' || this.currentChar == '-')
{
this.nextNo4DFA = 2;
}
else if(isDigit())
{
this.nextNo4DFA = 3;
}
//2
if(this.nextNo4DFA == 2)
{
this.nextChar();
if(isDigit())
{
this.nextNo4DFA = 3;
}
}
//3
if(this.nextNo4DFA == 3)
{
this.nextChar();
digitClosure();
if(isDone())
{
return new Token(Token.Number, this.currentToken);
}
else if(isPoint())
{
this.nextNo4DFA = 4;
}
}
//4
if(this.nextNo4DFA == 4)
{
this.nextChar();
if(isDigit())
{
this.nextNo4DFA = 5;
}
}
//5
if(this.nextNo4DFA == 5)
{
this.nextChar();
digitClosure();
if(isDone())
{
return new Token(Token.Float, this.currentToken);
}
}
System.out.println("error char at [" + this.currentChar + "].current parsed code:[" + this.currentToken+"] sourceCode:["+this.copySourceCode+"]");
return null;
}
private void digitClosure()
{
while (true)
{
if (isDigit())
{
this.nextChar();
continue;
}
else
break;
}
}
private boolean isPoint()
{
return this.currentChar == '.';
}
private boolean isDigit()
{
return Character.isDigit(this.currentChar);
}
private boolean isDone()
{
return this.currentChar == CharacterIterator.DONE;
}
private void add(char c)
{
this.currentToken += c;
}
private void clear()
{
this.currentToken = "";
}
public static void main(String[] args)
{
System.out.println(new NumberFloatV2("100").parse());
System.out.println(new NumberFloatV2("+100").parse());
System.out.println(new NumberFloatV2("-100").parse());
System.out.println(new NumberFloatV2("100.1").parse());
System.out.println(new NumberFloatV2("100.1.").parse());
// StringCharacterIterator iter = new StringCharacterIterator("100");
// for(char c = iter.first(); c != CharacterIterator.DONE; c = iter.next()) {
// System.out.println(c);
// }
}
}
package compiler.lexer;
public class Token
{
public static final int Number = 1;
public static final int Float = 2;
/**
* @param type
* @param name
*/
public Token(int type, String name)
{
super();
this.type = type;
Name = name;
}
private int type;
private String Name;
/**
* @return the type
*/
public int getType()
{
return type;
}
/**
* @param type the type to set
*/
public void setType(int type)
{
this.type = type;
}
/**
* @return the name
*/
public String getName()
{
return Name;
}
/**
* @param name the name to set
*/
public void setName(String name)
{
Name = name;
}
/* (non-Javadoc)
* @see java.lang.Object#toString()
*/
@Override
public String toString()
{
return "Token {Name=[" + Name + "], type=[" + type + "]}"; }
}
package compiler.lexer;
import java.text.CharacterIterator;
import java.text.StringCharacterIterator;
/**
*
* 输入:
* 输出:
* 描述: 区别于NumberFloatV2,这里是使用循环来实现,这种实现方式的好处是如果存在节点回退的情况也是可以处理的,例如从state=5编程state=2
* 用法:
*
*/
public class NumberFloatV3
{
static enum Type
{
Number, Float
}
private StringCharacterIterator iter = null;
private char currentChar;
private String currentToken = "";
private int state = 1;
private String copySourceCode;
/**
* @param iter
*/
public NumberFloatV3(String sourceCode)
{
this.iter = new StringCharacterIterator(sourceCode);
this.copySourceCode = sourceCode;
this.currentChar = iter.first();
}
public char nextChar()
{
add(this.currentChar);
this.currentChar = iter.next();
return currentChar;
}
public Token parse()
{
boolean isError = false;
while (true)
{
switch (this.state)
{
case 1:
if (this.currentChar == '+' || this.currentChar == '-')
{
this.state = 2;
}
else if (isDigit())
{
this.state = 3;
}
else
isError = true;
break;
case 2:
if (isDigit())
{
this.state = 3;
}
else
isError = true;
break;
case 3:
digitStar();
if (isDone())
{
return new Token(Token.Number, this.currentToken);
}
else if (isPoint())
{
this.state = 4;
}
else
isError = true;
break;
case 4:
if (isDigit())
{
this.state = 5;
}
else
isError = true;
break;
case 5:
digitStar();
if (isDone())
{
return new Token(Token.Float, this.currentToken);
}
else
isError = true;
break;
default:
break;
}
if(isError)
break;
this.nextChar();
}
System.out.println("error char at [" + this.currentChar + "] in parsed code:[" + this.currentToken
+ this.currentChar + "]");
return null;
}
private boolean digitStar()
{
boolean isFound = false;
while (true)
{
if (isDigit())
{
this.nextChar();
isFound = true;
continue;
}
else
break;
}
return isFound;
}
private boolean isPoint()
{
return this.currentChar == '.';
}
private boolean isDigit()
{
return Character.isDigit(this.currentChar);
}
private boolean isDone()
{
return this.currentChar == CharacterIterator.DONE;
}
private void add(char c)
{
this.currentToken += c;
}
private void clear()
{
this.currentToken = "";
}
public static void main(String[] args)
{
System.out.println(new NumberFloatV3("100").parse());
System.out.println(new NumberFloatV3("+100").parse());
System.out.println(new NumberFloatV3("-100").parse());
System.out.println(new NumberFloatV3("100.1").parse());
System.out.println(new NumberFloatV3("100.1.").parse());
// StringCharacterIterator iter = new StringCharacterIterator("100");
// for(char c = iter.first(); c != CharacterIterator.DONE; c =
// iter.next()) {
// System.out.println(c);
// }
}
}
package compiler.lexer;
import java.text.CharacterIterator;
import java.text.StringCharacterIterator;
import java.util.ArrayList;
import java.util.List;
import org.eclipse.jdt.core.dom.ThisExpression;
/**
*
* 输入:
* 输出:
* 描述: 区别于NumberFloatV3,这里功能新增加为识别多个token
* 用法:
*
*/
public class NumberFloatV4
{
static enum Type
{
Number, Float
}
private StringCharacterIterator iter = null;
private char currentChar;
private String currentToken = "";
private int state = 1;
private String copySourceCode;
/**
* @param iter
*/
public NumberFloatV4(String sourceCode)
{
this.iter = new StringCharacterIterator(sourceCode);
this.copySourceCode = sourceCode;
this.currentChar = iter.first();
}
public char nextChar()
{
if (this.currentChar != ' ')
add(this.currentChar);
this.currentChar = iter.next();
return currentChar;
}
public List parse()
{
List list = new ArrayList();
boolean isError = false;
while (true)
{
//过滤空格,在识别
if(this.currentToken.length() == 0)
{
blankStar();
if(isEnd())
break;
}
switch (this.state)
{
case 1:
if (this.currentChar == '+' || this.currentChar == '-')
{
this.state = 2;
}
else if (isDigit())
{
this.state = 3;
}
else
isError = true;
break;
case 2:
if (isDigit())
{
this.state = 3;
}
else
isError = true;
break;
case 3:
digitStar();
if (isDone())
{
addToken(list,Token.Number);
break;
}
else if (isPoint())
{
this.state = 4;
}
else
isError = true;
break;
case 4:
if (isDigit())
{
this.state = 5;
}
else
isError = true;
break;
case 5:
digitStar();
if (isDone())
{
addToken(list,Token.Float);
break;
}
else
isError = true;
break;
default:
break;
}
if(isError || isEnd())
break;
this.nextChar();
}
if (isError)
System.out.println("error char at [" + this.currentChar + "] in parsed code:[" + this.currentToken
+ this.currentChar + "]");
return list;
}
private void addToken(List list,int type)
{
list.add(new Token(type, this.currentToken));
this.state = 1;
this.currentToken = "";
}
private boolean blankStar()
{
boolean isFound = false;
while (true)
{
if (isBlank())
{
this.nextChar();
isFound = true;
continue;
}
else
break;
}
return isFound;
}
private boolean digitStar()
{
boolean isFound = false;
while (true)
{
if (isDigit())
{
this.nextChar();
isFound = true;
continue;
}
else
break;
}
return isFound;
}
private boolean isBlank()
{
return this.currentChar == ' ';
}
private boolean isPoint()
{
return this.currentChar == '.';
}
private boolean isDigit()
{
return Character.isDigit(this.currentChar);
}
private boolean isDone()
{
boolean isDone = isEnd() || isBlank();
return isDone;
}
private boolean isEnd()
{
return this.currentChar == CharacterIterator.DONE;
}
private void add(char c)
{
this.currentToken += c;
}
private void clear()
{
this.currentToken = "";
}
public static void main(String[] args)
{
System.out.println(new NumberFloatV4("100").parse());
System.out.println(new NumberFloatV4("+100").parse());
System.out.println(new NumberFloatV4("-100").parse());
System.out.println(new NumberFloatV4("100.1").parse());
System.out.println(new NumberFloatV4("100.1.").parse());
System.out.println(new NumberFloatV4(" 100.1 100 +100 -1.100 ").parse());
// StringCharacterIterator iter = new StringCharacterIterator("100");
// for(char c = iter.first(); c != CharacterIterator.DONE; c =
// iter.next()) {
// System.out.println(c);
// }
}
}
- 大小: 4.8 KB
