/**
* Expands the specified macro by replacing each macro usage
* with the stored definition.
*
* @param name the name of the macro to expand (for detecting cycles)
* @param definition the definition of the macro to expand
*
* @return the expanded definition of the macro.
*
* @throws MacroException when an error (such as a cyclic definition)
* occurs during expansion
*/
private RegExp expandMacro(String name, RegExp definition)
{
#if DEBUG_TRACE
log.WriteLine("expandMacro(String name = \"{0}\", RegExp definition = {1})", name, definition);
#endif // DEBUG_TRACE
// Out.print("checking macro "+name);
// Out.print("definition is "+definition);
switch (definition.type)
{
case sym.BAR:
case sym.CONCAT:
RegExp2 binary = (RegExp2)definition;
binary.r1 = expandMacro(name, binary.r1);
binary.r2 = expandMacro(name, binary.r2);
return(definition);
case sym.STAR:
case sym.PLUS:
case sym.QUESTION:
case sym.BANG:
case sym.TILDE:
RegExp1 unary = (RegExp1)definition;
unary.content = expandMacro(name, (RegExp)unary.content);
return(definition);
case sym.MACROUSE:
String usename = (String)((RegExp1)definition).content;
if (name.Equals(usename))
{
throw new MacroException(ErrorMessages.get(ErrorMessages.MACRO_CYCLE, name));
}
RegExp usedef = getDefinition(usename);
if (usedef == null)
{
throw new MacroException(ErrorMessages.get(ErrorMessages.MACRO_DEF_MISSING, usename, name));
}
markUsed(usename);
return(expandMacro(name, usedef));
case sym.STRING:
case sym.STRING_I:
case sym.CHAR:
case sym.CHAR_I:
case sym.CCLASS:
case sym.CCLASSNOT:
return(definition);
default:
throw new MacroException("unknown expression type " + definition.type + " in macro expansion"); //$NON-NLS-1$ //$NON-NLS-2$
}
}
/**
* Constructs a two state NFA for char class regexps,
* such that the NFA has
*
* exactly one start state,
* exactly one end state,
* no transitions leading out of the end state
* no transitions leading into the start state
*
* Assumes that regExp.isCharClass(macros) == true
*
* @param regExp the regular expression to construct the
* NFA for
*
* @return a pair of integers denoting the index of start
* and end state of the NFA.
*/
private void insertNFA(RegExp regExp, int start, int end)
{
switch (regExp.type)
{
case sym.BAR:
RegExp2 r = (RegExp2)regExp;
insertNFA(r.r1, start, end);
insertNFA(r.r2, start, end);
return;
case sym.CCLASS:
insertClassNFA((ArrayList)((RegExp1)regExp).content, start, end);
return;
case sym.CCLASSNOT:
insertNotClassNFA((ArrayList)((RegExp1)regExp).content, start, end);
return;
case sym.CHAR:
insertLetterNFA(
false, (char)((RegExp1)regExp).content,
start, end);
return;
case sym.CHAR_I:
insertLetterNFA(
true, (char)((RegExp1)regExp).content,
start, end);
return;
case sym.MACROUSE:
insertNFA(macros.getDefinition((String)((RegExp1)regExp).content),
start, end);
return;
}
throw new Exception("Unknown expression type " + regExp.type + " in NFA construction");
}
