94 lines
2.6 KiB
C++
94 lines
2.6 KiB
C++
module;
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#include <fstream>
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#include <iostream>
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// This module is the transpiler from WBT to HTML for site build
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export module wbt;
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export enum WBT_States {
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WBT_STATE_INIT,
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WBT_STATE_OPEN,
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WBT_STATE_EXPRESSION,
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WBT_STATE_CLOSE,
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};
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export class WBT_Parser {
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std::istream& input;
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std::ostream& output;
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public:
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explicit WBT_Parser(
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std::istream& i,
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std::ostream& o
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)
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: input(i), output(o) {
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}
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void output_char(const char c) const {
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output << c;
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}
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static void error(const std::string& msg, const int line, const int column) {
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std::cerr << "Error (" << line << "," << column << "): " << msg << std::endl;
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}
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void eval(const std::string& expr) const {
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output << "[EXPR: " << expr << "]";
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}
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void parse() const {
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auto state = WBT_STATE_INIT;
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std::string expr;
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auto line = 1;
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auto column = 1;
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while (input.peek() != std::char_traits<char>::eof()) {
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char c;
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input.get(c);
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// State machine
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switch (state) {
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case WBT_STATE_INIT:
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if (c == '{') {
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state = WBT_STATE_OPEN;
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} else {
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output_char(c);
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}
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break;
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case WBT_STATE_OPEN:
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if (c == '{') {
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state = WBT_STATE_EXPRESSION;
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} else {
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output_char('{');
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output_char(c);
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state = WBT_STATE_INIT;
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}
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break;
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case WBT_STATE_EXPRESSION:
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if (c == '}') {
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state = WBT_STATE_CLOSE;
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} else if (c == '{') {
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error("Invalid character inside of expression", line, column);
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return;
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} else {
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expr += c;
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}
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break;
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case WBT_STATE_CLOSE:
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if (c == '}') {
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eval(expr);
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expr.clear();
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state = WBT_STATE_INIT;
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} else {
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error("Unclosed expression", line, column);
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return;
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}
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break;
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}
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if (c == '\n') {
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line++;
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column = 1;
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} else {
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column++;
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}
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}
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}
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};
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