/* a parser that is composed of the previous parsers to get a number out of the input string.
* it succeeds iff the input line contains a floating point number. if successful, the result
* is given in res, if fails, the error is given in error and return value is NULL.*/
char* getNumber(char*p, float* res, int* err) {
char* e;
char t;
/* do we have anything to work on? */
if (p==NULL || *p == '\0') return NULL;
/* a nice trick by using or parser */
e = or(charIs(p, '-'), p);
e = allDigits(e);
e = or(charIs(e, '.'), e);
e = or(allDigits(e), e);
/* at the end of the previous 4 lines, we could have numbers in the following format -1, 1, -1. ,1.543, -65.45 */
/* if any of the above parsers had failed, return failure */
if (e == NULL) return e;
/* remove leading whitespace */
e = strip(e, " ");
/* if after removing all whitespaces we didnt hit either ',', end-of-line, or nothing was consumed at all,
* then the input that was given is wrong! fail this parser!*/
if ((!charIs(e, ',') && !charIs(e, '\n'))||e==p) {
*err = NUMBER_ERR;
return NULL;
}
/* if everything succeeded up till now, then e points to the rest of the input AFTER the valid float number,
* so we use a little trick to make it a float number:*/
t = *e; /* save the end of the consumed string */
*e = '\0'; /* mark it as end of line */
*res = (float)atof(p); /* use atof to transform the original input string (p) into the number */
*e=t; /* set the end of consumed string back to its original value */
return e; /* return the pointer to the rest of the unconsumed string */
}
PrologLexer::PrologLexer()
{
lexer.rules[Prolog::Spacing] = loop1(charOf(" \t\n\r"));
lexer.rules[Prolog::LParen] = str("(");
lexer.rules[Prolog::RParen] = str(")");
lexer.rules[Prolog::LBracket] = str("[");
lexer.rules[Prolog::RBracket] = str("]");
lexer.rules[Prolog::OnlyIf] = str(":-");
lexer.rules[Prolog::Eq] = str("=");
/*
lexer.rules[Prolog::Lt] = str("<");
lexer.rules[Prolog::Gt] = str(">");
lexer.rules[Prolog::Le] = str("<=");
lexer.rules[Prolog::Ge] = str(">=");
lexer.rules[Prolog::Ne] = str("<>");
*/
lexer.rules[Prolog::Dot] = str(".");
lexer.rules[Prolog::Comma] = str(",");
lexer.rules[Prolog::Semi] = str(";");
lexer.rules[Prolog::Bar] = str("|");
lexer.rules[Prolog::DomainsKw] = str("domains");
lexer.rules[Prolog::PredicatesKw] = str("predicates");
lexer.rules[Prolog::ClausesKw] = str("clauses");
lexer.rules[Prolog::AssertKw] = str("assert");
lexer.rules[Prolog::Str] = seq(str("\""),
loop(anyBut(choice(str("\""), str("\n")))),
str("\""));
shared_ptr<RegExp> digit = charIs([](QChar c) {
return c.isDigit();
},"<digit>");
shared_ptr<RegExp> letter = charIs([](QChar c) {
return c.isLetter();
}, "<letter>");
shared_ptr<RegExp> smallLetter = charIs([](QChar c) {
return c.isLower();
}, "<lowercase>");
shared_ptr<RegExp> capitalLetter = charIs([](QChar c) {
return c.isUpper();
}, "<uppercase>");
shared_ptr<RegExp> alpha = charIs([](QChar c) {
return c.isLetterOrNumber();
},"<alphanumeric>");
shared_ptr<RegExp> symbol = charOf("+-/*<>=");
shared_ptr<RegExp> digits = seq(loop1(digit), checkNo(letter));
shared_ptr<RegExp> smallLetterOrSymbol = choice(smallLetter, symbol);
shared_ptr<RegExp> alphaOrUnderscore = choice(alpha, str("_"));
shared_ptr<RegExp> alphaOrSymbol= choice(alpha, symbol);
lexer.rules[Prolog::Num] = seq(digits,
optional(seq(str("."), digits)));
lexer.rules[Prolog::Symbol] = seq(smallLetterOrSymbol, loop(choice(digit, alphaOrSymbol)));
lexer.rules[Prolog::Variable] = seq(choice(capitalLetter, str("_")),
loop(choice(digit, alphaOrUnderscore)));
}
/* A helper function for removing newlines, used for error reporting */
char* trimNewline(char* line)
{
int l = strlen(line);
int i=0;
if (oneOf(&line[l-1],"\r\n")) {
i++;
if (charIs(&line[l-2],'\r')) i++;
}
line[l-i]='\0';
return line;
}
