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package com.taobao.weex.utils;
import android.support.annotation.NonNull;
import java.util.LinkedHashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
/**
* Parser for function like "rotate(30 ) transform(50 , 20)".
* This class will translate the raw string presentation of a group of function(s) to give type
* according to the {@link com.taobao.weex.utils.FunctionParser.Mapper}
*/
public class FunctionParser<K, V> {
public static final char SPACE = ' ';
public static final char PERCENT = '%';
private Mapper<K, V> mapper;
private Lexer lexer;
/**
* Construct a function parser
* @param source the raw string representation of a group of function(s)
* @param mapper the mapping rule between string and corresponding type of object.
*/
public FunctionParser(@NonNull String source, @NonNull Mapper<K, V> mapper) {
this.lexer = new Lexer(source);
this.mapper = mapper;
}
/**
* Start to parse the raw string. The result will be stored in a sorted map where the order
* is defined by the function order in the raw string.
* @return
*/
public LinkedHashMap<K, V> parse() {
lexer.moveOn();
return definition();
}
private LinkedHashMap<K, V> definition() {
LinkedHashMap<K, V> result = new LinkedHashMap<>();
do {
result.putAll(function());
} while (lexer.getCurrentToken() == Token.FUNC_NAME);
return result;
}
private Map<K, V> function() {
List<String> list = new LinkedList<>();
String functionName = match(Token.FUNC_NAME);
match(Token.LEFT_PARENT);
list.add(match(Token.PARAM_VALUE));
while (lexer.getCurrentToken() == Token.COMMA) {
match(Token.COMMA);
list.add(match(Token.PARAM_VALUE));
}
match(Token.RIGHT_PARENT);
return mapper.map(functionName, list);
}
private String match(Token token) {
if (token == lexer.getCurrentToken()) {
String value = lexer.getCurrentTokenValue();
lexer.moveOn();
return value;
}
throw new WXInterpretationException("Token doesn't match");
}
private enum Token {
FUNC_NAME, PARAM_VALUE, LEFT_PARENT, RIGHT_PARENT, COMMA
}
public interface Mapper<K, V> {
/**
* Map one function to a specified type of object
* @param functionName the name of the raw function.
* @param raw the list of parameter of the raw function
* @return the expected mapping relationship, where the key in the map is the same as the
* functionName, and the value in the map is the type of object that expected by user.
*/
Map<K, V> map(String functionName, List<String> raw);
}
private static class WXInterpretationException extends RuntimeException {
private WXInterpretationException(String msg) {
super(msg);
}
}
/**
* Lexer for the parser. For now, digit, alphabet, '(', ')', '.', ',', '+', '-' and '%' is
* valid character, and '(', ')', ',', parameter value and function name is valid token.
* Parameter value is defined as "(?i)[\+-]?[0-9]+(\.[0-9]+)?(%||deg||px)?" while function
* name is defined as "[a-zA-Z]+".
*/
private static class Lexer {
private static final String LEFT_PARENT = "(";
private static final String RIGHT_PARENT = ")";
private static final String COMMA = ",";
private static final char A_LOWER = 'a';
private static final char Z_LOWER = 'z';
private static final char A_UPPER = 'A';
private static final char Z_UPPER = 'Z';
private static final char ZERO = '0';
private static final char NINE = '9';
private static final char DOT = '.';
private static final char MINUS = '-';
private static final char PLUS = '+';
private String source;
private Token current;
private String value;
private int pointer = 0;
private Lexer(String source) {
this.source = source;
}
private Token getCurrentToken() {
return current;
}
private String getCurrentTokenValue() {
return value;
}
private boolean moveOn() {
int start = pointer;
char curChar;
while (pointer < source.length()) {
curChar = source.charAt(pointer);
if (curChar == SPACE) {
if (start == pointer++) {
start++;
} else {
break;
}
} else if (isCharacterOrDigit(curChar) || curChar == DOT
|| curChar == PERCENT || curChar == MINUS || curChar == PLUS) {
pointer++;
} else {
if (start == pointer) {
pointer++;
}
break;
}
}
if (start != pointer) {
String symbol = source.substring(start, pointer);
moveOn(symbol);
return true;
} else {
current = null;
value = null;
return false;
}
}
private void moveOn(String token) {
if (LEFT_PARENT.equals(token)) {
current = Token.LEFT_PARENT;
value = LEFT_PARENT;
} else if (RIGHT_PARENT.equals(token)) {
current = Token.RIGHT_PARENT;
value = RIGHT_PARENT;
} else if (COMMA.equals(token)) {
current = Token.COMMA;
value = COMMA;
} else if (isFuncName(token)) {
current = Token.FUNC_NAME;
value = token;
} else {
current = Token.PARAM_VALUE;
value = token;
}
}
private boolean isFuncName(CharSequence funcName) {
char letter;
for (int i = 0; i < funcName.length(); i++) {
letter = funcName.charAt(i);
if (!((A_LOWER <= letter && letter <= Z_LOWER) ||
(A_UPPER <= letter && letter <= Z_UPPER) ||
letter == MINUS)) {
return false;
}
}
return true;
}
private void reset() {
pointer = 0;
value = null;
current = null;
}
private boolean isCharacterOrDigit(char letter) {
return (ZERO <= letter && letter <= NINE) || (A_LOWER <= letter && letter <= Z_LOWER) ||
(A_UPPER <= letter && letter <= Z_UPPER);
}
}
}