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Diffstat (limited to 'util/qlalr/examples/qparser/qparser.h')
-rw-r--r-- | util/qlalr/examples/qparser/qparser.h | 111 |
1 files changed, 111 insertions, 0 deletions
diff --git a/util/qlalr/examples/qparser/qparser.h b/util/qlalr/examples/qparser/qparser.h new file mode 100644 index 0000000..e3ff61d --- /dev/null +++ b/util/qlalr/examples/qparser/qparser.h @@ -0,0 +1,111 @@ +#ifndef QPARSER_H +#define QPARSER_H + +#include <QtCore/QSharedDataPointer> +#include <QtCore/QVarLengthArray> + +template <typename _Parser, typename _Table, typename _Value = int> +class QParser: protected _Table +{ +public: + QParser(); + ~QParser(); + + bool parse(); + + inline _Value &sym(int index); + +private: + inline int nextToken() + { + return static_cast<_Parser*> (this)->nextToken(); + } + + inline void consumeRule(int rule) + { + static_cast<_Parser*> (this)->consumeRule(rule); + } + + enum { DefaultStackSize = 128 }; + + struct Data: public QSharedData + { + Data(): stackSize (DefaultStackSize), tos (0) {} + + QVarLengthArray<int, DefaultStackSize> stateStack; + QVarLengthArray<_Value, DefaultStackSize> parseStack; + int stackSize; + int tos; + + void reallocateStack() { + stackSize <<= 1; + stateStack.resize(stackSize); + parseStack.resize(stackSize); + } + }; + + QSharedDataPointer<Data> d; +}; + +template <typename _Parser, typename _Table, typename _Value> +inline _Value &QParser<_Parser, _Table, _Value>::sym(int n) +{ + return d->parseStack [d->tos + n - 1]; +} + +template <typename _Parser, typename _Table, typename _Value> +QParser<_Parser, _Table, _Value>::QParser(): + d(new Data()) +{ +} + +template <typename _Parser, typename _Table, typename _Value> +QParser<_Parser, _Table, _Value>::~QParser() +{ +} + +template <typename _Parser, typename _Table, typename _Value> +bool QParser<_Parser, _Table, _Value>::parse() +{ + const int INITIAL_STATE = 0; + + d->tos = 0; + d->reallocateStack(); + + int act = d->stateStack[++d->tos] = INITIAL_STATE; + int token = -1; + + forever { + if (token == -1 && - _Table::TERMINAL_COUNT != _Table::action_index[act]) + token = nextToken(); + + act = _Table::t_action(act, token); + + if (d->stateStack[d->tos] == _Table::ACCEPT_STATE) + return true; + + else if (act > 0) { + if (++d->tos == d->stackSize) + d->reallocateStack(); + + d->parseStack[d->tos] = d->parseStack[d->tos - 1]; + d->stateStack[d->tos] = act; + token = -1; + } + + else if (act < 0) { + int r = - act - 1; + d->tos -= _Table::rhs[r]; + act = d->stateStack[d->tos++]; + consumeRule(r); + act = d->stateStack[d->tos] = _Table::nt_action(act, _Table::lhs[r] - _Table::TERMINAL_COUNT); + } + + else break; + } + + return false; +} + + +#endif // QPARSER_H |