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package info.bliki.wiki.template.expr;
import info.bliki.wiki.template.expr.ast.ASTNode;
import info.bliki.wiki.template.expr.ast.IParserFactory;
import info.bliki.wiki.template.expr.ast.NumberNode;
import info.bliki.wiki.template.expr.operator.ASTNodeFactory;
import info.bliki.wiki.template.expr.operator.InfixOperator;
import info.bliki.wiki.template.expr.operator.Operator;
import info.bliki.wiki.template.expr.operator.PostfixOperator;
import info.bliki.wiki.template.expr.operator.PrefixOperator;
/**
* Create an expression of the ASTNode class-hierarchy from a math
* formulas string representation.
*
* See Operator
* -precedence parser for the idea, how to parse the operators depending on
* their precedence.
*/
public class Parser extends Scanner {
/**
* Use '('...')' as brackets for arguments
*/
boolean fRelaxedSyntax;
public Parser() {
this(ASTNodeFactory.MMA_STYLE_FACTORY, false);
}
public Parser(final boolean relaxedSyntax) throws SyntaxError {
this(ASTNodeFactory.MMA_STYLE_FACTORY, relaxedSyntax);
}
public Parser(IParserFactory factory, final boolean relaxedSyntax) throws SyntaxError {
super();
fRelaxedSyntax = relaxedSyntax;
fFactory = factory;
}
public void setFactory(final IParserFactory factory) {
this.fFactory = factory;
}
public IParserFactory getFactory() {
return fFactory;
}
/**
* Determine the current PrefixOperator
*
* @return null if no prefix operator could be determined
*/
private PrefixOperator determinePrefixOperator() {
Operator oper = null;
for (int i = 0; i < fOperList.size(); i++) {
oper = (Operator) fOperList.get(i);
if (oper instanceof PrefixOperator) {
return (PrefixOperator) oper;
}
}
return null;
}
/**
* Determine the current PostfixOperator
*
* @return null if no postfix operator could be determined
*/
private PostfixOperator determinePostfixOperator() {
Operator oper = null;
for (int i = 0; i < fOperList.size(); i++) {
oper = (Operator) fOperList.get(i);
if (oper instanceof PostfixOperator) {
return (PostfixOperator) oper;
}
}
return null;
}
/**
* Determine the current BinaryOperator
*
* @return null if no binary operator could be determined
*/
private InfixOperator determineBinaryOperator() {
Operator oper = null;
for (int i = 0; i < fOperList.size(); i++) {
oper = (Operator) fOperList.get(i);
if (oper instanceof InfixOperator) {
return (InfixOperator) oper;
}
}
return null;
}
private ASTNode parsePrimary() {
if (fToken == TT_OPERATOR) {
final Operator oper = determinePrefixOperator();
if (oper instanceof PrefixOperator) {
getNextToken();
final ASTNode temp = parseLookaheadOperator(oper.getPrecedence());
if (oper.getFunctionName().equals("PreMinus")) {
// special cases for negative numbers
if (temp instanceof NumberNode) {
((NumberNode) temp).toggleSign();
return temp;
}
}
return ((PrefixOperator) oper).createFunction(fFactory, temp);
}
throwSyntaxError("Operator: " + fOperatorString + " is no prefix operator.");
}
return getFactor();
}
private ASTNode parseLookaheadOperator(final int min_precedence) {
ASTNode rhs = parsePrimary();
Operator operLookahead;
InfixOperator binOper;
while (true) {
final int lookahead = fToken;
if (lookahead != TT_OPERATOR) {
break;
}
operLookahead = determineBinaryOperator();
if (operLookahead instanceof InfixOperator) {
binOper = (InfixOperator) operLookahead;
if (binOper.getPrecedence() > min_precedence) {
rhs = parseOperators(rhs, operLookahead.getPrecedence());
continue;
} else if ((binOper.getPrecedence() == min_precedence) && (binOper.getGrouping() == InfixOperator.RIGHT_ASSOCIATIVE)) {
rhs = parseOperators(rhs, operLookahead.getPrecedence());
continue;
}
} else {
operLookahead = determinePostfixOperator();
if (operLookahead instanceof PostfixOperator) {
if (operLookahead.getPrecedence() > min_precedence) {
getNextToken();
rhs = ((PostfixOperator) operLookahead).createFunction(fFactory, rhs);
continue;
}
}
}
break;
}
return rhs;
}
/**
* See Operator
* -precedence parser for the idea, how to parse the operators depending
* on their precedence.
*
* @param lhs
* the already parsed left-hand-side of the operator
* @param min_precedence
* @return
*/
private ASTNode parseOperators(ASTNode lhs, final int min_precedence) {
ASTNode rhs = null;
Operator oper;
while (true) {
if (fToken != TT_OPERATOR) {
break;
}
oper = determineBinaryOperator();
if (oper instanceof InfixOperator) {
if (oper.getPrecedence() >= min_precedence) {
getNextToken();
rhs = parseLookaheadOperator(oper.getPrecedence());
lhs = ((InfixOperator) oper).createFunction(fFactory, lhs, rhs);
continue;
}
} else {
oper = determinePostfixOperator();
if (oper instanceof PostfixOperator) {
getNextToken();
lhs = ((PostfixOperator) oper).createFunction(fFactory, lhs);
continue;
}
throwSyntaxError("Operator: " + fOperatorString + " is no infix or postfix operator.");
}
break;
}
return lhs;
}
/**
* Parse the given expression String into an ASTNode.
*
* @param expression
* a formula string which should be parsed.
* @return the parsed ASTNode representation of the given formula string
* @throws SyntaxError
*/
public ASTNode parse(final String expression) throws SyntaxError {
initialize(expression);
final ASTNode temp = parseOperators(parsePrimary(), 0);
if (fToken != TT_EOF) {
if (fToken == TT_PRECEDENCE_CLOSE) {
throwSyntaxError("Too many closing ')'; End-of-file not reached.");
}
if (fOperatorString == "E") {
fCurrentPosition--;
}
throwSyntaxError("End-of-file not reached.");
}
return temp;
}
/**
* Method Declaration.
*
* @return
* @see
*/
private ASTNode getNumber(final boolean negative) throws SyntaxError {
ASTNode temp = null;
final Object[] result = getNumberString();
String number = (String) result[0];
final int numFormat = ((Integer) result[1]).intValue();
try {
if (negative) {
number = '-' + number;
}
if (numFormat < 0) {
temp = fFactory.createDouble(number);
} else {
temp = fFactory.createInteger(number, numFormat);
}
} catch (final Throwable e) {
throwSyntaxError("Number format error: " + number, number.length());
}
getNextToken();
return temp;
}
private ASTNode getFactor() throws SyntaxError {
ASTNode temp;
if (fToken == TT_CONSTANT) {
temp = fFactory.createSymbol(fOperatorString);
getNextToken();
return temp;
}
if (fToken == TT_DIGIT) {
return getNumber(false);
}
if (fToken == TT_PRECEDENCE_OPEN) {
getNextToken();
temp = parseOperators(parsePrimary(), 0);
if (fToken != TT_PRECEDENCE_CLOSE) {
throwSyntaxError("\')\' expected.");
}
getNextToken();
return temp;
}
switch (fToken) {
case TT_PRECEDENCE_CLOSE:
throwSyntaxError("Too much open ) in factor.");
break;
}
throwSyntaxError("Error in factor at character: '" + fCurrentChar + "' (" + fToken + ")");
return null;
}
}