Beginning to make a parse_regex function for regex searches
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#ifndef REGEX
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#define REGEX
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#include <regex>
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#endif
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#ifndef VECTOR
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#define VECTOR
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#include <vector>
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#endif
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#ifndef FN_IS_NUMBER
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#define FN_IS_NUMBER
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#include "is_number.cpp"
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#endif
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#include <iostream>
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std::vector<std::string> parse_regex(std::string expression) {
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/***
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I hate this with every ounce of my being.
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I can only apologize.
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vector<string> parse_regex(string expression):
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Splits a regular expression into its component parts
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Returns a vector<string> where each string is one component part of the expression, independently usable as its own expression
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NOT FINISHED
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***/
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// The vector we will return
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std::vector<std::string> parsed_expression;
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// A flag to set when we hit a backslash (\)
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bool escaped = false;
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// A flag to set when we hit a caret (^)
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bool caret = false;
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// A flag to set when we're entering multiple characters into one element of the vector
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bool multi_char_entry = false;
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bool square_brackets_open = false;
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bool curly_braces_open = false;
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bool curly_braces_received_number = false;
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bool curly_braces_received_comma = false;
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std::string curly_braces_buffer;
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int parentheses_level = 0;
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// Iterate through each character in the string
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for(char& c : expression) {
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std::string part(1, c);
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int current_index = parsed_expression.size()-1;
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if (square_brackets_open || parentheses_level > 0 || escaped || caret) {
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multi_char_entry = true;
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} else {
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multi_char_entry = false;
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}
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if (parentheses_level < 0) {
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parentheses_level = 0;
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}
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// What do we do with this character?
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switch(c) {
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case '\\':
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escaped = !escaped;
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if (multi_char_entry) {
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parsed_expression[current_index] += part;
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} else {
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parsed_expression.push_back(part);
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}
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caret = false;
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break;
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case '[':
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if (multi_char_entry) {
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parsed_expression[current_index] += part;
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} else {
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parsed_expression.push_back(part);
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}
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if (!escaped) {
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square_brackets_open = true;
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}
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escaped = false;
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caret = false;
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break;
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case ']':
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if (multi_char_entry) {
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parsed_expression[current_index] += part;
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} else {
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parsed_expression.push_back(part);
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}
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if (!escaped) {
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square_brackets_open = false;
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}
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escaped = false;
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caret = false;
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break;
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case '(':
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if (!escaped) {
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parentheses_level++;
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}
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if (multi_char_entry) {
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parsed_expression[current_index] += part;
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} else {
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parsed_expression.push_back(part);
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}
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escaped = false;
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caret = false;
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break;
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case ')':
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if (!escaped) {
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parentheses_level--;
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}
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if (multi_char_entry) {
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parsed_expression[current_index] += part;
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} else {
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parsed_expression.push_back(part);
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}
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escaped = false;
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caret = false;
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break;
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case '{':
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if (!escaped && !square_brackets_open) {
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curly_braces_open = true;
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curly_braces_buffer += part;
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} else {
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if (multi_char_entry) {
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parsed_expression[current_index] += part;
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} else {
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parsed_expression.push_back(part);
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}
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}
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escaped = false;
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caret = false;
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break;
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case '}':
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if (curly_braces_open && curly_braces_received_number) {
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curly_braces_open = false;
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curly_braces_received_number = false;
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curly_braces_received_comma = false;
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curly_braces_buffer += part;
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parsed_expression[current_index] += curly_braces_buffer;
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curly_braces_buffer = "";
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} else {
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if (multi_char_entry) {
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parsed_expression[current_index] += part;
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} else {
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parsed_expression.push_back(part);
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}
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}
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escaped = false;
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caret = false;
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break;
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case '+':
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parsed_expression[current_index] += part;
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escaped = false;
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caret = false;
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break;
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case '*':
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parsed_expression[current_index] += part;
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escaped = false;
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caret = false;
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break;
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case '?':
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parsed_expression[current_index] += part;
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escaped = false;
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caret = false;
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break;
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case '^':
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if (!escaped) {
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caret = true;
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}
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if (multi_char_entry) {
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parsed_expression[current_index] += part;
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} else {
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parsed_expression.push_back(part);
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}
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escaped = false;
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break;
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case '$':
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parsed_expression[current_index] += part;
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escaped = false;
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caret = false;
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break;
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default:
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if (curly_braces_open) {
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// The curly braces ("{}") only have special meaning if they're followed by an INTEGER
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// Ie, [a-z]{2} or [a-z]{2,3} or [a-z]{2,}
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// Does not count: [a-z]{two} (this expression would look for '{' 't' 'w' 'o' '}' literal)
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// Does not count: [a-z]{,}
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if (
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(!is_number(part) && part != ",")
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|| (part == "," && (!curly_braces_received_number || curly_braces_received_comma))
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) {
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// If we're getting something other than a number,
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// (or ONE SINGLE comma AFTER we've already received a number)
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// Give up on the curly_braces_buffer
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curly_braces_open = false;
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curly_braces_received_number = false;
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// Push each of the characters we had been saving for the buffer
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// Back into the output vector one by one
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for (int i=0; i<curly_braces_buffer.size(); i++) {
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std::string bufferpart(1, curly_braces_buffer[i]);
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if (multi_char_entry) {
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parsed_expression[current_index] += bufferpart;
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} else {
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parsed_expression.push_back(bufferpart);
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}
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}
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// Clear the buffer
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curly_braces_buffer = "";
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if (multi_char_entry) {
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parsed_expression[current_index] += part;
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} else {
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parsed_expression.push_back(part);
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}
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} else {
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curly_braces_received_number = true;
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if (part == ",") {
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curly_braces_received_comma = true;
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}
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curly_braces_buffer += part;
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}
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} else {
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if (multi_char_entry) {
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parsed_expression[current_index] += part;
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} else {
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parsed_expression.push_back(part);
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}
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}
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escaped = false;
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caret = false;
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}
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}
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return parsed_expression;
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}
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