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/*
* This file is part of evQueue
*
* evQueue is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* evQueue is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with evQueue. If not, see <http://www.gnu.org/licenses/>.
*
* Author: Thibault Kummer <bob@coldsource.net>
*/
#include <XPathParser.h>
#include <XPathTokens.h>
#include <Exception.h>
#include <DOMNode.h>
using namespace std;
// Parse one token from the XPath expression
// It might not be possible to exactly define token type now, disambiguish will do the rest
Token *XPathParser::parse_token(const string &s, int *pos)
{
// Skip spaces
while(s[*pos]==' ' && *pos<s.length())
(*pos)++;
int base_pos = *pos + 1; // For human position use 1 as base
if(*pos>=s.length())
return 0;
// Match single characters syntax
if(s[*pos]=='(')
{
*pos= *pos+1;
return (new TokenSyntax(LPAR))->SetInitialPosition(base_pos);
}
else if(s[*pos]==')')
{
*pos = *pos+1;
return (new TokenSyntax(RPAR))->SetInitialPosition(base_pos);
}
else if(s[*pos]=='[')
{
*pos = *pos+1;
return (new TokenSyntax(LSQ))->SetInitialPosition(base_pos);
}
else if(s[*pos]==']')
{
*pos = *pos+1;
return (new TokenSyntax(RSQ))->SetInitialPosition(base_pos);
}
else if(s[*pos]==',')
{
*pos = *pos+1;
return (new TokenSyntax(COMMA))->SetInitialPosition(base_pos);
}
// Match path delimiters
if(s.substr(*pos,2)=="//")
{
*pos = *pos+2;
return (new TokenSyntax(DSLASH))->SetInitialPosition(base_pos);
}
else if(s[*pos]=='/')
{
*pos = *pos+1;
return (new TokenSyntax(SLASH))->SetInitialPosition(base_pos);
}
// Match operators
if(s[*pos]=='+')
{
*pos = *pos+1;
return (new TokenOP(PLUS))->SetInitialPosition(base_pos);
}
else if(s[*pos]=='-' && (*pos+1>=s.length() || !isdigit(s[*pos+1]))) // Not not confuse - 1 (OP + LIT_INT) and -1 (LIT_INT)
{
*pos = *pos+1;
return (new TokenOP(MINUS))->SetInitialPosition(base_pos);
}
else if(s[*pos]=='*')
{
*pos = *pos+1;
return (new TokenOP(MULT))->SetInitialPosition(base_pos); // Could also be a wildcard, see disambiguish_mult()
}
else if(s[*pos]=='=')
{
*pos = *pos+1;
return (new TokenOP(EQ))->SetInitialPosition(base_pos);
}
else if(s.substr(*pos,2)=="!=")
{
*pos = *pos+2;
return (new TokenOP(NEQ))->SetInitialPosition(base_pos);
}
else if(s[*pos]=='<')
{
*pos = *pos+1;
return (new TokenOP(LT))->SetInitialPosition(base_pos);
}
else if(s.substr(*pos,2)=="<=")
{
*pos = *pos+2;
return (new TokenOP(LEQ))->SetInitialPosition(base_pos);
}
else if(s[*pos]=='>')
{
*pos = *pos+1;
return (new TokenOP(GT))->SetInitialPosition(base_pos);
}
else if(s.substr(*pos,2)==">=")
{
*pos = *pos+2;
return (new TokenOP(GEQ))->SetInitialPosition(base_pos);
}
else if(s.substr(*pos,1)=="|")
{
*pos = *pos+1;
return (new TokenOP(PIPE))->SetInitialPosition(base_pos);
}
// Match strings
if(s[*pos]=='\'' || s[*pos]=='\"')
{
string buf;
int i = *pos+1;
if(s[*pos]=='\'')
while(i<s.length() && s[i]!='\'')
buf += s[i++];
else if(s[*pos]=='\"')
while(i<s.length() && s[i]!='\"')
buf += s[i++];
if(i>=s.length() || (s[i]!='\'' && s[i]!='\"'))
throw Exception("XPath Parser","Invalid string : end delimiter expected for token at character "+to_string(base_pos));
*pos = i + 1;
return (new TokenString(buf))->SetInitialPosition(base_pos);
}
// Match Integer or Float
if(s[*pos]>='0' && s[*pos]<='9' || s[*pos]=='-')
{
bool is_float = false;
string buf;
if(s[*pos]=='-')
{
buf += '-';
*pos++;
}
int i = *pos;
while(i<s.length() && ((s[i]>='0' && s[i]<='9') || s[i]=='.'))
{
if(s[i]=='.')
{
if(is_float)
throw Exception("XPath Parser","Invalid float : only one dot is allowed for token at character "+to_string(base_pos));
else
is_float = true;
}
buf += s[i++];
}
try
{
*pos = i;
if(is_float)
return (new TokenFloat(stod(buf)))->SetInitialPosition(base_pos);
else
return (new TokenInt(stoi(buf)))->SetInitialPosition(base_pos);
}
catch(...)
{
throw Exception("XPath Parser","Invalid int or float at character "+to_string(base_pos));
}
}
// At this point we can only have Node name, Attribute or Function.
// Text operators can be confused with node or function names, see disambiguish_operators()
string buf;
string buf2;
int i = *pos;
if(s.substr(i,2)=="..")
{
*pos+=2;
return (new TokenNodeName(".."))->SetInitialPosition(base_pos);
}
else if(s[i]=='.')
{
*pos+=1;
return (new TokenNodeName("."))->SetInitialPosition(base_pos);
}
bool is_attribute = false;
bool is_axis = false;
if(s.substr(i,2)=="@*")
{
*pos+=2;
return (new TokenAttrName("*"))->SetInitialPosition(base_pos);
}
else if(s[i]=='@')
{
is_attribute = true;
i++;
}
while(i<s.length() && (isalnum(s[i]) || s[i]=='_' || s[i]=='-' || s[i]==':'))
{
if(s[i]==':')
{
if(is_axis)
throw Exception("XPath Parser","Unexpected ':' in axis name at character "+to_string(base_pos));
is_axis = true;
if(s.substr(i,3)=="::*")
{
buf2 = "*";
i+=3;
break;
}
else if(s.substr(i,2)=="::")
{
i+=2;
continue;
}
}
if(!is_axis)
buf += s[i++];
else
buf2 += s[i++];
}
if(buf=="")
throw Exception("XPath Parser","Invalid node or function name at character "+to_string(base_pos));
if(is_axis && buf2=="")
throw Exception("XPath Parser","Invalid axis filter node at character "+to_string(base_pos));
// Skip spaces
while(s[i]==' ' && i<s.length())
i++;
// Function names only differ from node names because they have parenthesis
*pos = i;
if(is_attribute)
return (new TokenAttrName(buf))->SetInitialPosition(base_pos);
else if(is_axis)
return (new TokenAxis(buf,buf2))->SetInitialPosition(base_pos);
else if(s[i]=='(')
return (new TokenFunc(buf))->SetInitialPosition(base_pos);
else
return (new TokenNodeName(buf))->SetInitialPosition(base_pos);
}
// Create a TokenExpr from a string by calling parse_token
vector<Token *> XPathParser::parse_expr(const string expr)
{
vector<Token *> v;
try
{
// Parse tokens
int current_pos = 0;
Token *token;
while(current_pos!=expr.length() && (token = parse_token(expr,¤t_pos)))
v.push_back(token);
}
catch(Exception &e)
{
// Free already created tokens
for(int i=0;i<v.size();i++)
delete v.at(i);
throw e;
}
return v;
}
// Create sub expressions with each group of parenthesis
// Functions arguments are treated as expressions
TokenExpr *XPathParser::resolve_parenthesis(const vector<Token *> &v, int *current_pos)
{
TokenExpr *expr_token = new TokenExpr();
int i;
// Loop until end of document or end of expression (ie right parenthesis)
for(i=*current_pos;i<v.size() && v.at(i)->GetType()!=RPAR;i++)
{
// Left parenthesis, we have a sub expression
if(v.at(i)->GetType()==LPAR)
{
delete v.at(i);
i++;
// Recursively build sub expression
expr_token->expr_tokens.push_back(resolve_parenthesis(v,&i));
if(i>=v.size() || v.at(i)->GetType()!=RPAR)
{
*current_pos = i;
delete expr_token;
throw Exception("XPath Parser","Missing closing parenthesis");
}
delete v.at(i);
}
else
expr_token->expr_tokens.push_back(v.at(i)); // Simply push token to current expression
}
*current_pos = i;
return expr_token;
}
// Look for expressions after function names and parse arguments
// Function arguments are treated as arrays of expressions, one expression for each argument
void XPathParser::prepare_functions(TokenExpr *expr)
{
TokenFunc *func;
for(int i=0;i<expr->expr_tokens.size();i++)
{
// Look for a function name
if(expr->expr_tokens.at(i)->GetType()==FUNC)
{
func = (TokenFunc *)expr->expr_tokens.at(i);
// Function names must by followed by an expression (ie the parameters)
if(i+1>=expr->expr_tokens.size() || expr->expr_tokens.at(i+1)->GetType()!=EXPR)
throw Exception("XPath Parser","Missing function parameters"+func->LogInitialPosition());
TokenExpr *parameters = ((TokenExpr *)expr->expr_tokens.at(i+1));
TokenExpr *parameter = 0;
if(parameters->expr_tokens.size()>0)
parameter = new TokenExpr();
// Split parameters expression on comma to separate parameters
for(int j=0;j<parameters->expr_tokens.size();)
{
if(parameters->expr_tokens.at(j)->GetType()==COMMA)
{
// Store last found parameters and prepare for new one
if(parameter->expr_tokens.size()==0)
{
delete parameter;
throw Exception("XPath Parser","Empty function parameter"+func->LogInitialPosition());
}
prepare_functions(parameter);
func->args.push_back(parameter);
parameter = new TokenExpr();
delete parameters->expr_tokens.at(j);
parameters->expr_tokens.erase(parameters->expr_tokens.begin()+j);
continue;
}
parameter->expr_tokens.push_back(parameters->expr_tokens.at(j));
parameters->expr_tokens.erase(parameters->expr_tokens.begin()+j);
}
// Store last found parameter
if(parameter)
{
if(parameter->expr_tokens.size()==0)
{
delete parameter;
throw Exception("XPath Parser","Empty function parameter"+func->LogInitialPosition());
}
prepare_functions(parameter);
func->args.push_back(parameter);
}
// Remove expression as everything has been transfered to function arguments
expr->expr_tokens.erase(expr->expr_tokens.begin()+i+1);
delete parameters;
}
else if(expr->expr_tokens.at(i)->GetType()==EXPR)
prepare_functions((TokenExpr *)expr->expr_tokens.at(i));
}
}
// Create expressions from filters (expressions between square brackets)
// Filters are removed from XPath expression and directly attached to node names
void XPathParser::prepare_filters(TokenExpr *expr)
{
for(int i=0;i<expr->expr_tokens.size();i++)
{
// Look for node names as only them can have filters
if(expr->expr_tokens.at(i)->GetType()==LSQ)
{
// Catch filter expression until right bracket ('filter end')
TokenExpr *filter = new TokenExpr();
int j = i+1;
while(j<expr->expr_tokens.size() && expr->expr_tokens.at(j)->GetType()!=RSQ)
{
filter->expr_tokens.push_back(expr->expr_tokens.at(j));
j++;
}
if(j>=expr->expr_tokens.size() || expr->expr_tokens.at(j)->GetType()!=RSQ)
{
filter->expr_tokens.clear();
delete filter;
throw Exception("XPath Parser","Missing closing square on filter"+expr->expr_tokens.at(i)->LogInitialPosition());
}
if(filter->expr_tokens.size()==0)
{
filter->expr_tokens.clear();
delete filter;
throw Exception("XPath Parser","Empty filter"+expr->expr_tokens.at(i)->LogInitialPosition());
}
delete expr->expr_tokens.at(i);
delete expr->expr_tokens.at(j);
expr->expr_tokens.erase(expr->expr_tokens.begin()+i,expr->expr_tokens.begin()+j+1);
expr->expr_tokens.insert(expr->expr_tokens.begin()+i,new TokenFilter(filter));
}
else if(expr->expr_tokens.at(i)->GetType()==FUNC)
{
// Parse function parameters as they contains expressions
TokenFunc *func = (TokenFunc *)expr->expr_tokens.at(i);
for(int j=0;j<func->args.size();j++)
prepare_filters(func->args.at(j));
}
else if(expr->expr_tokens.at(i)->GetType()==EXPR) // Parse sub expresionns
prepare_filters((TokenExpr *)expr->expr_tokens.at(i));
}
}
void XPathParser::prepare_paths(TokenExpr *expr)
{
TokenExpr *subexpr = 0;
int replace_from;
for(int i=0;i<=expr->expr_tokens.size();i++)
{
// Look for paths items and create subexpression
TOKEN_TYPE token_type = i<expr->expr_tokens.size()?expr->expr_tokens.at(i)->GetType():ENDLINE;
if(token_type==SLASH || token_type==DSLASH || token_type==NODENAME || token_type==ATTRNAME || token_type==AXIS || token_type==FUNC || token_type==FILTER)
{
if(token_type==FUNC)
{
// Parse function parameters as they can contain paths
TokenFunc *func = (TokenFunc *)expr->expr_tokens.at(i);
for(int j=0;j<func->args.size();j++)
prepare_paths(func->args.at(j));
}
else if(token_type==FILTER)
{
TokenFilter *filter = (TokenFilter *)expr->expr_tokens.at(i);
prepare_paths(filter->filter);
}
if(subexpr==0)
{
replace_from = i;
subexpr = new TokenExpr();
}
subexpr->expr_tokens.push_back(expr->expr_tokens.at(i));
}
else
{
if(token_type==EXPR) // Parse sub expresionns
prepare_paths((TokenExpr *)expr->expr_tokens.at(i));
if(subexpr)
{
expr->expr_tokens.erase(expr->expr_tokens.begin()+replace_from,expr->expr_tokens.begin()+i);
i = replace_from;
expr->expr_tokens.insert(expr->expr_tokens.begin()+i,subexpr);
subexpr = 0;
}
}
}
}
// Mult operator (1 * 1) can be confused with node wildcard (/node/*/node)
// On parsing '*' is always resolved as operator, transform to node name when needed
void XPathParser::disambiguish_mult(TokenExpr *expr)
{
for(int i=0;i<expr->expr_tokens.size();i++)
{
// Look for operator MULT
if(expr->expr_tokens.at(i)->GetType()==OP && ((TokenOP *)expr->expr_tokens.at(i))->op==MULT)
{
// When found as first token, we have a node name
// When preceding token is /, // or an operator we have a node name
// Case 1 : '*' (expression begin)
// Case 2 : 'node/* (after /)
// Case 3 : //* (after //)
// Case 4 : 2 * * (after an operator)
if(i==0 || expr->expr_tokens.at(i-1)->GetType()==SLASH || expr->expr_tokens.at(i-1)->GetType()==DSLASH || expr->expr_tokens.at(i-1)->GetType()==OP)
{
int pos = expr->expr_tokens.at(i)->GetInitialPosition();
delete expr->expr_tokens.at(i);
expr->expr_tokens.erase(expr->expr_tokens.begin()+i);
expr->expr_tokens.insert(expr->expr_tokens.begin()+i,(new TokenNodeName("*"))->SetInitialPosition(pos));
}
}
else if(expr->expr_tokens.at(i)->GetType()==EXPR)
disambiguish_mult((TokenExpr *)expr->expr_tokens.at(i)); // Recursively parse sub expressions
}
}
// Disambiguish operators that have textual names
void XPathParser::disambiguish_operators(TokenExpr *expr)
{
for(int i=0;i<expr->expr_tokens.size();i++)
{
// Operators can be mistaken for Node names of Function names
if(expr->expr_tokens.at(i)->GetType()==NODENAME || expr->expr_tokens.at(i)->GetType()==FUNC)
{
// Get potential operator name
string opname;
if(expr->expr_tokens.at(i)->GetType()==NODENAME)
opname = ((TokenNodeName *)expr->expr_tokens.at(i))->name;
else if(expr->expr_tokens.at(i)->GetType()==FUNC)
opname = ((TokenFunc *)expr->expr_tokens.at(i))->name;
// This an operator if :
// 1. Name matches a potential operator
// 2. It is preceded by the below tokens
if(i>0 && (opname=="and" || opname=="or" || opname=="div" || opname=="mod"))
{
Token *prec = expr->expr_tokens.at(i-1);
if(
prec->GetType()==LIT_STR
|| prec->GetType()==LIT_INT
|| prec->GetType()==LIT_FLOAT
|| prec->GetType()==LIT_BOOL
|| prec->GetType()==NODENAME
|| prec->GetType()==ATTRNAME
|| prec->GetType()==FUNC
|| prec->GetType()==RPAR
|| prec->GetType()==RSQ
|| prec->GetType()==EXPR
)
{
// Replace token with operator
int pos = expr->expr_tokens.at(i)->GetInitialPosition();
delete expr->expr_tokens.at(i);
expr->expr_tokens.erase(expr->expr_tokens.begin()+i);
if(opname=="and")
expr->expr_tokens.insert(expr->expr_tokens.begin()+i,(new TokenOP(AND))->SetInitialPosition(pos));
else if(opname=="or")
expr->expr_tokens.insert(expr->expr_tokens.begin()+i,(new TokenOP(OR))->SetInitialPosition(pos));
else if(opname=="div")
expr->expr_tokens.insert(expr->expr_tokens.begin()+i,(new TokenOP(DIV))->SetInitialPosition(pos));
else if(opname=="mod")
expr->expr_tokens.insert(expr->expr_tokens.begin()+i,(new TokenOP(MOD))->SetInitialPosition(pos));
}
}
}
else if(expr->expr_tokens.at(i)->GetType()==EXPR)
disambiguish_operators((TokenExpr *)expr->expr_tokens.at(i));
}
}
// Parse the whole XPath expression and return the corresponding expression
TokenExpr *XPathParser::Parse(std::string xpath_expression)
{
vector<Token *> v;
TokenExpr *parsed_expr = 0;
int current_pos = 0;
try
{
v = parse_expr(xpath_expression);
parsed_expr = resolve_parenthesis(v,¤t_pos);
if(current_pos!=v.size())
throw Exception("XPath Parser","Unexpected closing parenthesis");
disambiguish_mult(parsed_expr);
disambiguish_operators(parsed_expr);
prepare_functions(parsed_expr);
prepare_filters(parsed_expr);
prepare_paths(parsed_expr);
}
catch(Exception &e)
{
if(parsed_expr)
delete parsed_expr;
for(int i=current_pos;i<v.size();i++)
delete v.at(i);
throw e;
}
return parsed_expr;
}
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