StringParseResult ParseStringExpression(const char *expr, int start, int end)
{
StringParseResult lhs = ParseTerm(expr, start, end);
if (lhs.result)
{
StringParseResult rhs = ParseStringExpression(expr, lhs.position, end);
if (rhs.result)
{
StringExpression *ret = xcalloc(1, sizeof(StringExpression));
ret->op = CONCAT;
ret->val.concat.lhs = lhs.result;
ret->val.concat.rhs = rhs.result;
return (StringParseResult) {ret, rhs.position};
}
else
{
return lhs;
}
}
else
{
return lhs;
}
}
static ParseResult ParsePrimary(const char *expr, int start, int end)
{
if (start < end && expr[start] == '(')
{
ParseResult res = ParseExpression(expr, start + 1, end);
if (res.result)
{
/* Check there is a matching ')' at the end */
if (res.position < end && expr[res.position] == ')')
{
return (ParseResult)
{
res.result, res.position + 1
};
}
else
{
/* Didn't find a matching bracket. Give up */
FreeExpression(res.result);
return (ParseResult)
{
NULL, res.position
};
}
}
else
{
return res;
}
}
else
{
StringParseResult strres = ParseStringExpression(expr, start, end);
if (strres.result)
{
Expression *res = xcalloc(1, sizeof(Expression));
res->op = EVAL;
res->val.eval.name = strres.result;
return (ParseResult)
{
res, strres.position
};
}
else
{
return (ParseResult)
{
NULL, strres.position
};
}
}
}
static StringParseResult ParseQname(const char *expr, int start, int end)
{
StringParseResult lhs, rhs;
StringExpression *ret, *subret, *dot;
lhs = ParseStringExpression(expr, start, end);
if (!lhs.result)
{
return lhs;
}
if (lhs.position == end || expr[lhs.position] != '.')
{
return lhs;
}
rhs = ParseStringExpression(expr, lhs.position + 1, end);
if (!rhs.result)
{
FreeStringExpression(lhs.result);
return rhs;
}
dot = xcalloc(1, sizeof(StringExpression));
dot->op = LITERAL;
dot->val.literal.literal = xstrdup(".");
subret = xcalloc(1, sizeof(StringExpression));
subret->op = CONCAT;
subret->val.concat.lhs = dot;
subret->val.concat.rhs = rhs.result;
ret = xcalloc(1, sizeof(StringExpression));
ret->op = CONCAT;
ret->val.concat.lhs = lhs.result;
ret->val.concat.rhs = subret;
return (StringParseResult) {ret, rhs.position};
}
