124 lines
2.2 KiB
Ragel
124 lines
2.2 KiB
Ragel
#include <vector>
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#include <string>
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#include <unordered_map>
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#include <memory>
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#include <stdio.h>
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#include <assert.h>
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#include "mpw-shell.h"
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%%{
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machine classify;
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alphtype unsigned char;
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ws = [ \t];
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IF = /if/i;
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ELSE = /else/i;
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END = /end/i;
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EVALUATE = /evaluate/i;
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main := |*
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IF %eof{ return command_if; };
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IF ws => {return command_if; };
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ELSE %eof{ return command_else;};
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ELSE ws => { return command_else; };
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ELSE ws+ IF %eof{ return command_else_if; };
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ELSE ws+ IF ws => {return command_else_if; };
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END %eof{ return command_end; };
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END ws => {return command_end; };
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EVALUATE %eof{ return command_evaluate; };
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EVALUATE ws => {return command_evaluate; };
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*|;
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}%%
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int classify(const std::string &line) {
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%% write data;
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int cs;
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int act;
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const unsigned char *p = (const unsigned char *)line.data();
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const unsigned char *pe = (const unsigned char *)line.data() + line.size();
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const unsigned char *eof = pe;
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const unsigned char *te, *ts;
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%%write init;
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%%write exec;
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return 0;
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}
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/*
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* Generates a linked-list of commands. Why? Because it also checks
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* for shell-special syntax (currently if / else /end only) and
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* adds pointers to make executing them easier.
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*
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*/
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command_ptr build_command(const std::vector<std::string> &lines) {
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std::vector<command_ptr> if_stack;
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command_ptr head;
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command_ptr prev;
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for (const auto &line : lines) {
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if (line.empty()) continue;
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int type = classify(line);
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command_ptr c = std::make_shared<command>(type, line);
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if (!head) head = c;
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if (!prev) prev = c;
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else {
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prev->next = c;
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prev = c;
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}
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// if stack...
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switch (type) {
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case command_if:
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if_stack.push_back(c);
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break;
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case command_else:
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case command_else_if:
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if (if_stack.empty()) {
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throw std::runtime_error("### MPW Shell - Else must be within if ... end.");
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}
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if_stack.back()->alternate = c;
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if_stack.back() = c;
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break;
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case command_end:
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if (if_stack.empty()) {
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throw std::runtime_error("### MPW Shell - Extra end command.");
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}
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if_stack.back()->alternate = c;
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if_stack.pop_back();
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break;
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}
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}
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if (!if_stack.empty()) {
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throw std::runtime_error("### MPW Shell - Unterminated if command.");
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}
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return head;
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}
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