boxberry/src/BBBParser.cc

#include "BBBParser.h"

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>

int BBBParser::get() {
	int ch = stream_.get();
	if (ch == '\n') {
		line_ += 1;
		ch_ = 1;
	} else {
		ch_ += 1;
	}

	return ch;
}

void BBBParser::skip(char expected) {
	int ch = get();
	if (ch == EOF) {
		error(std::string("Expected '") + expected + "', got EOF");
	} else if (ch != expected) {
		error(std::string("Expected '") + expected + "', got '" + (char)ch + "'");
	}
}

void BBBParser::error(std::string msg) {
	throw BBBParseError(std::to_string(line_) + ":" + std::to_string(ch_) + ": " + msg);
}

static bool isWhitespace(int ch) {
	if (ch == ' ' || ch == '\t' || ch == '\r' || ch == '\n')
		return true;
	return false;
}

void BBBParser::skipWhitespaceLine() {
	char ch;
	while (isWhitespace(ch = peek()) && ch != '\r' && ch != '\n')
		get();
}

void BBBParser::skipWhitespace() {
	while (isWhitespace(peek()))
		get();
}

char BBBParser::parseEscape() {
	skip(); // '\'
	int ch;
	switch (ch = get()) {
		case EOF:
			error("Unexpected EOF");

		case 'n':
			return '\n';

		case 'r':
			return '\r';

		case 't':
			return '\t';

		default:
			return (char)ch;
	}
}

void BBBParser::parseExpansion(const Variables &vars, std::vector<std::string> &values) {
	skip(); // '$'

	auto appendVar = [&](const std::string &name) {
		if (name.size() == 0)
			return;

		auto it = vars.find(name);
		if (it == vars.end())
			return;

		auto &vec = it->second;
		for (auto &part: vec) {
			values.push_back(part);
		}
	};

	std::string str;
	switch (peek()) {
	case '{':
		skip();
		parseString(vars, str, '}');
		skip('}');
		appendVar(str);
		break;

	default:
		if (!parseString(vars, str)) {
			error("No identifier after $. Did you mean '\\$'?");
		}

		appendVar(str);
	}
}

void BBBParser::parseQuotedExpansion(const Variables &vars, std::string &content) {
	skip(); // '$'

	auto appendVar = [&](const std::string &name) {
		if (name.size() == 0)
			return;

		auto it = vars.find(name);
		if (it == vars.end())
			return;

		auto &vec = it->second;
		bool first = true;
		for (auto &part: vec) {
			if (!first) {
				content += ' ';
			}

			first = false;
			content += part;
		}
	};

	std::string str;
	switch (peek()) {
	case '{':
		skip();
		parseString(vars, str, '}');
		skip('}');
		appendVar(str);
		break;

	default:
		if (!parseString(vars, str, '"')) {
			error("No identifier after $. Did you mean '\\$'?");
		}

		appendVar(str);
	}
}

void BBBParser::parseQuotedString(const Variables &vars, std::string &content) {
	skip(); // '"'

	int ch;
	while ((ch = peek()) != EOF) {
		switch (ch) {
		case EOF:
			error("Unexpected EOF");

		case '\\':
			content.push_back(parseEscape());
			break;

		case '$':
			parseQuotedExpansion(vars, content);
			break;

		case '"':
			skip();
			return;

		default:
			content.push_back(get());
			break;
		}
	}
}

bool BBBParser::parseString(const Variables &vars, std::string &content, int sep) {
	bool success = false;
	int ch;
	while (1) {
		ch = peek();
		if ((sep > 0 && ch == sep) || isWhitespace(ch)) {
			return success;
		}

		switch (ch) {
		case '=':
		case EOF:
			return success;

		case '\\':
			content.push_back(parseEscape());
			break;

		case '"':
			parseQuotedString(vars, content);
			success = true;
			break;

		default:
			content.push_back(get());
			success = true;
			break;
		}
	}
}

void BBBParser::parseLine(const Variables &vars, std::vector<std::string> &values) {
	std::string value;
	while (true) {
		skipWhitespaceLine();
		if (peek() == EOF) {
			break;
		} else if (peek() == '$') {
			parseExpansion(vars, values);
			continue;
		}

		if (!parseString(vars, value)) {
			break;
		}

		values.push_back(std::move(value));
		value.clear();
	}
}

void BBBParser::parse(Variables &vars) {
	std::string key, value;
	std::vector<std::string> values;

	skipWhitespace();
	if (!parseString(vars, key)) {
		return;
	}

	skipWhitespace();
	skip('=');

	while (true) {
		skipWhitespace();

		if (peek() == EOF) {
			break;
		} else if (peek() == '$') {
			parseExpansion(vars, values);
			continue;
		}

		if (!parseString(vars, value)) {
			break;
		}

		skipWhitespace();
		if (peek() == '=') {
			if (key.size() == 0) {
				error("No variable on the left hand side of '='");
			}

			skip();
			vars[key] = std::move(values);
			key = std::move(value);
			value.clear();
		} else {
			values.push_back(std::move(value));
			value.clear();
		}
	}

	vars[key] = std::move(values);
}