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Eval

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- Merged libexpr Eval support.
This commit is contained in:
Paul Beckingham 2014-01-02 01:25:18 -05:00
parent f6d0be24da
commit 0fd9c495bc
3 changed files with 479 additions and 0 deletions
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1
src/CMakeLists.txt
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@ -17,6 +17,7 @@ set (task_SRCS A3.cpp A3.h
Directory.cpp Directory.h
Duration.cpp Duration.h
E9.cpp E9.h
Eval.cpp Eval.h
File.cpp File.h
Hooks.cpp Hooks.h
ISO8601.cpp ISO8601.h

413
src/Eval.cpp Normal file
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////////////////////////////////////////////////////////////////////////////////
//
// Copyright 2013 - 2014, Paul Beckingham, Federico Hernandez.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
//
// http://www.opensource.org/licenses/mit-license.php
//
////////////////////////////////////////////////////////////////////////////////
#include <iostream>
#include <time.h>
#include <Eval.h>
// Supported operators, borrowed from C++, particularly the precedence.
// Note: table is sorted by length of operator string, so searches match
// longest first.
static struct
{
std::string op;
int precedence;
char type;
char associativity;
} operators[] =
{
// Operator Precedence Type Associativity
{ "and", 5, 'b', 'l' }, // Conjunction
{ "xor", 4, 'b', 'l' }, // Disjunction
{ "or", 3, 'b', 'l' }, // Disjunction
{ "<=", 10, 'b', 'l' }, // Less than or equal
{ ">=", 10, 'b', 'l' }, // Greater than or equal
{ "!~", 9, 'b', 'l' }, // Regex non-match
{ "!=", 9, 'b', 'l' }, // Inequal
{ "==", 9, 'b', 'l' }, // Equal
{ "=", 9, 'b', 'l' }, // Equal
{ "^", 16, 'b', 'r' }, // Exponent
{ ">", 10, 'b', 'l' }, // Greater than
{ "~", 9, 'b', 'l' }, // Regex match
{ "!", 15, 'u', 'r' }, // Not
{ "_hastag_", 9, 'b', 'l'}, // +tag [Pseudo-op]
{ "_notag_", 9, 'b', 'l'}, // -tag [Pseudo-op]
// { "-", 15, 'u', 'r' }, // Unary minus
{ "*", 13, 'b', 'l' }, // Multiplication
{ "/", 13, 'b', 'l' }, // Division
{ "%", 13, 'b', 'l' }, // Modulus
{ "+", 12, 'b', 'l' }, // Addition
{ "-", 12, 'b', 'l' }, // Subtraction
{ "<", 10, 'b', 'l' }, // Less than
{ "(", 0, 'b', 'l' }, // Precedence start
{ ")", 0, 'b', 'l' }, // Precedence end
};
#define NUM_OPERATORS (sizeof (operators) / sizeof (operators[0]))
////////////////////////////////////////////////////////////////////////////////
Eval::Eval ()
: _ambiguity (true)
, _debug (false)
{
}
////////////////////////////////////////////////////////////////////////////////
Eval::~Eval ()
{
}
////////////////////////////////////////////////////////////////////////////////
void Eval::addSource (bool (*source)(const std::string&, Variant&))
{
_sources.push_back (source);
}
////////////////////////////////////////////////////////////////////////////////
void Eval::evaluateInfixExpression (const std::string& e, Variant& v) const
{
// Reduce e to a vector of tokens.
Lexer l (e);
l.ambiguity (_ambiguity);
std::vector <std::pair <std::string, Lexer::Type> > tokens;
std::string token;
Lexer::Type type;
while (l.token (token, type))
{
tokens.push_back (std::pair <std::string, Lexer::Type> (token, type));
if (_debug)
std::cout << "# token infix '" << token << "' " << Lexer::type_name (type) << "\n";
}
// Convert infix --> postfix.
infixToPostfix (tokens);
// Call the postfix evaluator.
evaluatePostfixStack (tokens, v);
}
////////////////////////////////////////////////////////////////////////////////
void Eval::evaluatePostfixExpression (const std::string& e, Variant& v) const
{
// Reduce e to a vector of tokens.
Lexer l (e);
l.ambiguity (_ambiguity);
std::vector <std::pair <std::string, Lexer::Type> > tokens;
std::string token;
Lexer::Type type;
while (l.token (token, type))
{
tokens.push_back (std::pair <std::string, Lexer::Type> (token, type));
if (_debug)
std::cout << "# token postfix '" << token << "' " << Lexer::type_name (type) << "\n";
}
// Call the postfix evaluator.
evaluatePostfixStack (tokens, v);
}
////////////////////////////////////////////////////////////////////////////////
void Eval::ambiguity (bool value)
{
_ambiguity = value;
}
////////////////////////////////////////////////////////////////////////////////
void Eval::debug ()
{
_debug = true;
}
////////////////////////////////////////////////////////////////////////////////
void Eval::evaluatePostfixStack (
const std::vector <std::pair <std::string, Lexer::Type> >& tokens,
Variant& result) const
{
if (tokens.size () == 0)
{
std::cout << "No expression to evaluate.\n";
result = Variant ("");
return;
}
// This is stack used by the postfix evaluator.
std::vector <Variant> values;
std::vector <std::pair <std::string, Lexer::Type> >::const_iterator token;
for (token = tokens.begin (); token != tokens.end (); ++token)
{
// Unary operator.
if (token->second == Lexer::typeOperator &&
token->first == "!")
{
Variant right = values.back ();
values.pop_back ();
values.push_back (! right);
}
// Binary operators.
else if (token->second == Lexer::typeOperator)
{
if (_debug)
std::cout << "# [" << values.size () << "] eval operator '" << token->first << "'\n";
Variant right = values.back ();
values.pop_back ();
Variant left = values.back ();
values.pop_back ();
// Ordering these by anticipation frequency of use is a good idea.
if (token->first == "and") left = left && right;
else if (token->first == "or") left = left || right;
else if (token->first == "&&") left = left && right;
else if (token->first == "||") left = left || right;
else if (token->first == "<") left = left < right;
else if (token->first == "<=") left = left <= right;
else if (token->first == ">") left = left > right;
else if (token->first == ">=") left = left >= right;
else if (token->first == "==") left = left.operator== (right);
else if (token->first == "=") left = left.operator== (right);
else if (token->first == "!=") left = left.operator!= (right);
else if (token->first == "+") left += right;
else if (token->first == "-") left -= right;
else if (token->first == "*") left *= right;
else if (token->first == "/") left /= right;
else if (token->first == "^") left ^= right;
else if (token->first == "%") left %= right;
else if (token->first == "xor") left = left.operator_xor (right);
else if (token->first == "~") left = left.operator_match (right);
else if (token->first == "!~") left = left.operator_nomatch (right);
else
std::cout << "# Unrecognized operator '" << token->first << "'\n";
values.push_back (left);
}
else
{
Variant v (token->first);
switch (token->second)
{
case Lexer::typeNumber:
case Lexer::typeHex:
v.cast (Variant::type_integer);
break;
case Lexer::typeDecimal:
v.cast (Variant::type_real);
break;
case Lexer::typeOperator:
std::cout << "# Error: operator unexpected.\n";
break;
case Lexer::typeIdentifier:
{
std::vector <bool (*)(const std::string&, Variant&)>::const_iterator source;
for (source = _sources.begin (); source != _sources.end (); ++source)
{
if ((*source) (token->first, v))
{
if (_debug)
std::cout << "# [" << values.size () << "] eval source '" << token->first << "' --> '" << (std::string) v << "'\n";
break;
}
}
// An identifier that fails lookup is a string.
if (source == _sources.end ())
{
v.cast (Variant::type_string);
if (_debug)
std::cout << "# [" << values.size () << "] eval source failed '" << token->first << "'\n";
}
}
break;
case Lexer::typeDate:
v.cast (Variant::type_date);
break;
case Lexer::typeDuration:
v.cast (Variant::type_duration);
break;
// Nothing to do.
case Lexer::typeString:
default:
break;
}
values.push_back (v);
if (_debug)
std::cout << "# [" << values.size () << "] eval push '" << token->first << "' " << Lexer::type_name (token->second) << "\n";
}
}
// Should only be one value left on the stack.
if (values.size () != 1)
if (_debug)
std::cout << "# Error: Unexpected stack size: " << values.size () << "\n";
result = values[0];
}
////////////////////////////////////////////////////////////////////////////////
// Dijkstra Shunting Algorithm.
// http://en.wikipedia.org/wiki/Shunting-yard_algorithm
//
// While there are tokens to be read:
// Read a token.
// If the token is an operator, o1, then:
// while there is an operator token, o2, at the top of the stack, and
// either o1 is left-associative and its precedence is less than or
// equal to that of o2,
// or o1 is right-associative and its precedence is less than that
// of o2,
// pop o2 off the stack, onto the output queue;
// push o1 onto the stack.
// If the token is a left parenthesis, then push it onto the stack.
// If the token is a right parenthesis:
// Until the token at the top of the stack is a left parenthesis, pop
// operators off the stack onto the output queue.
// Pop the left parenthesis from the stack, but not onto the output queue.
// If the token at the top of the stack is a function token, pop it onto
// the output queue.
// If the stack runs out without finding a left parenthesis, then there
// are mismatched parentheses.
// If the token is a number, then add it to the output queue.
//
// When there are no more tokens to read:
// While there are still operator tokens in the stack:
// If the operator token on the top of the stack is a parenthesis, then
// there are mismatched parentheses.
// Pop the operator onto the output queue.
// Exit.
//
void Eval:: infixToPostfix (
std::vector <std::pair <std::string, Lexer::Type> >& infix) const
{
// Short circuit.
if (infix.size () == 1)
return;
// Result.
std::vector <std::pair <std::string, Lexer::Type> > postfix;
// Shunting yard.
std::vector <std::pair <std::string, Lexer::Type> > op_stack;
// Operator characteristics.
char type;
int precedence;
char associativity;
std::vector <std::pair <std::string, Lexer::Type> >::iterator token;
for (token = infix.begin (); token != infix.end (); ++token)
{
if (token->second == Lexer::typeOperator &&
token->first == "(")
{
op_stack.push_back (*token);
}
else if (token->second == Lexer::typeOperator &&
token->first == ")")
{
while (op_stack.size () &&
op_stack.back ().first != "(")
{
postfix.push_back (op_stack.back ());
op_stack.pop_back ();
}
if (op_stack.size ())
op_stack.pop_back ();
else
throw std::string ("Mismatched parentheses in expression");
}
else if (token->second == Lexer::typeOperator &&
identifyOperator (token->first, type, precedence, associativity))
{
char type2;
int precedence2;
char associativity2;
while (op_stack.size () > 0 &&
identifyOperator (op_stack.back ().first, type2, precedence2, associativity2) &&
((associativity == 'l' && precedence <= precedence2) ||
(associativity == 'r' && precedence < precedence2)))
{
postfix.push_back (op_stack.back ());
op_stack.pop_back ();
}
op_stack.push_back (*token);
}
else
{
postfix.push_back (*token);
}
}
while (op_stack.size ())
{
if (op_stack.back ().first == "(" ||
op_stack.back ().first == ")")
throw std::string ("Mismatched parentheses in expression");
postfix.push_back (op_stack.back ());
op_stack.pop_back ();
}
infix = postfix;
}
////////////////////////////////////////////////////////////////////////////////
bool Eval::identifyOperator (
const std::string& op,
char& type,
int& precedence,
char& associativity) const
{
for (unsigned int i = 0; i < NUM_OPERATORS; ++i)
{
if (operators[i].op == op)
{
type = operators[i].type;
precedence = operators[i].precedence;
associativity = operators[i].associativity;
return true;
}
}
return false;
}
////////////////////////////////////////////////////////////////////////////////

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src/Eval.h Normal file
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////////////////////////////////////////////////////////////////////////////////
//
// Copyright 2013 - 2014, Paul Beckingham, Federico Hernandez.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
//
// http://www.opensource.org/licenses/mit-license.php
//
////////////////////////////////////////////////////////////////////////////////
#ifndef INCLUDED_EVAL
#define INCLUDED_EVAL
#include <vector>
#include <string>
#include <Lexer.h>
#include <Variant.h>
class Eval
{
public:
Eval ();
virtual ~Eval ();
Eval (const Eval&); // Not implemented.
Eval& operator= (const Eval&); // Not implemented.
bool operator== (const Eval&); // Not implemented.
void addSource (bool (*fn)(const std::string&, Variant&));
void evaluateInfixExpression (const std::string&, Variant&) const;
void evaluatePostfixExpression (const std::string&, Variant&) const;
void ambiguity (bool);
void debug ();
private:
void evaluatePostfixStack (const std::vector <std::pair <std::string, Lexer::Type> >&, Variant&) const;
void infixToPostfix (std::vector <std::pair <std::string, Lexer::Type> >&) const;
bool identifyOperator (const std::string&, char&, int&, char&) const;
private:
std::vector <bool (*)(const std::string&, Variant&)> _sources;
bool _ambiguity;
bool _debug;
};
#endif
////////////////////////////////////////////////////////////////////////////////