Parsodus/templates/c++/lr.cpp

66 lines
2.4 KiB
C++

/*
* This software is provided 'as-is', without any express or implied warranty. In no event will the authors be held liable for any damages arising from the use of this software.
*
* Permission is granted to anyone to use this software for any purpose, including commercial applications, and to alter it and redistribute it freely, subject to the following restrictions:
*
* 1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required.
*
* 2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
*
* 3. This notice may not be removed or altered from any source distribution.
*/
#include "{{name}}.h"
#define TABLE {{name}}___Table___{{name}}
#define REDUCE_COUNT {{name}}___Num_Reduces___{{name}}
const std::uint64_t TABLE[{{num_states}}][{{num_symbols}}] = {
{{#states}}
{ {{#actions}}({{action}} | ({{data}}) << 2),{{/actions}}
{{#gotos}}(({{.}}) << 2),{{/gotos}} },
{{/states}}
};
const unsigned char REDUCE_COUNT[{{num_rules}}] = { {{#rules}}{{rhs_length}},{{/rules}} };
bool {{name}}<bool>::parse() {
std::stack<std::uint64_t> stateStack;
using Sym = {{name}}_Symbol;
stateStack.push(0);
Sym tok = lex();
while (true) {
std::uint64_t act = TABLE[stateStack.top()][static_cast<std::uint64_t>(tok)];
switch (act & 0x3) {
case ERROR:
return false;
case SHIFT:
stateStack.push(act >> 2);
tok = lex();
break;
case REDUCE:
{
std::uint64_t tmp = act >> 2;
Sym symbol = static_cast<Sym>(tmp >> 31);
std::uint32_t rule = tmp & ((1ull << 31) - 1);
for (unsigned char i = 0; i < REDUCE_COUNT[rule]; i++) {
stateStack.pop();
}
stateStack.push(TABLE[stateStack.top()][static_cast<std::uint64_t>(symbol)] >> 2);
}
break;
case ACCEPT:
assert(stateStack.size() == 2);
return true;
default:
//IMPOSSIBLE
break;
}
}
}