src/lexer.cc

/*
	Copyright 2012-2014 Santeri Piippo
	All rights reserved.

	Redistribution and use in source and binary forms, with or without
	modification, are permitted provided that the following conditions
	are met:

	1. Redistributions of source code must retain the above copyright
	   notice, this list of conditions and the following disclaimer.
	2. Redistributions in binary form must reproduce the above copyright
	   notice, this list of conditions and the following disclaimer in the
	   documentation and/or other materials provided with the distribution.
	3. The name of the author may not be used to endorse or promote products
	   derived from this software without specific prior written permission.

	THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
	IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
	IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
	INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

#include <cstring>
#include "lexer.h"

static string_list	g_file_name_stack;
static lexer*		g_main_lexer = null;

// =============================================================================
//
lexer::lexer()
{
	assert (g_main_lexer == null);
	g_main_lexer = this;
}

// =============================================================================
//
lexer::~lexer()
{
	g_main_lexer = null;
}

// =============================================================================
//
void lexer::process_file (string file_name)
{
	g_file_name_stack << file_name;
	FILE* fp = fopen (file_name, "r");

	if (fp == null)
		error ("couldn't open %1 for reading: %2", file_name, strerror (errno));

	lexer_scanner sc (fp);
	check_file_header (sc);

	while (sc.get_next_token())
	{
		// Preprocessor commands:
		if (sc.get_token_type() == tk_hash)
		{
			must_get_next_from_scanner (sc, tk_symbol);

			if (sc.get_token_text() == "include")
			{
				must_get_next_from_scanner (sc, tk_string);
				string file_name = sc.get_token_text();

				if (g_file_name_stack.contains (file_name))
					error ("attempted to #include %1 recursively", sc.get_token_text());

				process_file (file_name);
			}
			else
				error ("unknown preprocessor directive \"#%1\"", sc.get_token_text());
		}
		else
		{
			token tok;
			tok.file = file_name;
			tok.line = sc.get_line();
			tok.column = sc.get_column();
			tok.type = sc.get_token_type();
			tok.text = sc.get_token_text();

			// devf ("Token #%1: %2:%3:%4: %5 (%6)\n", m_tokens.size(),
			//	tok.file, tok.line, tok.column, describe_token (&tok), describe_token_type (tok.type));

			m_tokens << tok;
		}
	}

	m_token_position = m_tokens.begin() - 1;
	g_file_name_stack.remove (file_name);
}

// ============================================================================
//
static bool is_valid_header (string header)
{
	if (header.ends_with ("\n"))
		header.remove_from_end (1);

	string_list tokens = header.split (" ");

	if (tokens.size() != 2 || tokens[0] != "#!botc" || tokens[1].empty())
		return false;

	string_list nums = tokens[1].split (".");

	if (nums.size() == 2)
		nums << "0";
	elif (nums.size() != 3)
		return false;

	bool ok_a, ok_b, ok_c;
	long major = nums[0].to_long (&ok_a);
	long minor = nums[1].to_long (&ok_b);
	long patch = nums[2].to_long (&ok_c);

	if (!ok_a || !ok_b || !ok_c)
		return false;

	if (VERSION_NUMBER < MAKE_VERSION_NUMBER (major, minor, patch))
		error ("The script file requires " APPNAME " v%1, this is v%2",
			make_version_string (major, minor, patch), get_version_string (e_short_form));

	return true;
}

// ============================================================================
//
void lexer::check_file_header (lexer_scanner& sc)
{
	if (!is_valid_header (sc.read_line()))
		error ("Not a valid botscript file! File must start with '#!botc <version>'");
}

// =============================================================================
//
bool lexer::get_next (e_token req)
{
	iterator pos = m_token_position;

	if (m_tokens.is_empty())
		return false;

	m_token_position++;

	if (is_at_end() || (req != tk_any && get_token_type() != req))
	{
		m_token_position = pos;
		return false;
	}

	return true;
}

// =============================================================================
//
void lexer::must_get_next (e_token tt)
{
	if (!get_next())
		error ("unexpected EOF");

	if (tt != tk_any)
		must_be (tt);
}

// =============================================================================
// eugh..
//
void lexer::must_get_next_from_scanner (lexer_scanner& sc, e_token tt)
{
	if (!sc.get_next_token())
		error ("unexpected EOF");

	if (tt != tk_any && sc.get_token_type() != tt)
	{	// TODO
		token tok;
		tok.type = sc.get_token_type();
		tok.text = sc.get_token_text();

		error ("at %1:%2: expected %3, got %4",
			g_file_name_stack.last(),
			sc.get_line(),
			describe_token_type (tt),
			describe_token (&tok));
	}
}

// =============================================================================
//
void lexer::must_get_any_of (const list<e_token>& toks)
{
	if (!get_next())
		error ("unexpected EOF");

	for (e_token tok : toks)
		if (get_token_type() == tok)
			return;

	string toknames;

	for (const e_token& tok_type : toks)
	{
		if (&tok_type == &toks.last())
			toknames += " or ";
		elif (toknames.is_empty() == false)
			toknames += ", ";

		toknames += describe_token_type (tok_type);
	}

	error ("expected %1, got %2", toknames, describe_token (get_token()));
}

// =============================================================================
//
int lexer::get_one_symbol (const string_list& syms)
{
	if (!get_next())
		error ("unexpected EOF");

	if (get_token_type() == tk_symbol)
	{
		for (int i = 0; i < syms.size(); ++i)
		{
			if (syms[i] == get_token()->text)
				return i;
		}
	}

	error ("expected one of %1, got %2", syms, describe_token (get_token()));
	return -1;
}

// =============================================================================
//
void lexer::must_be (e_token tok)
{
	if (get_token_type() != tok)
		error ("expected %1, got %2", describe_token_type (tok),
			describe_token (get_token()));
}

// =============================================================================
//
string lexer::describe_token_private (e_token tok_type, lexer::token* tok)
{
	if (tok_type < tk_last_named_token)
		return "\"" + lexer_scanner::get_token_string (tok_type) + "\"";

	switch (tok_type)
	{
		case tk_symbol:	return tok ? tok->text : "a symbol";
		case tk_number:	return tok ? tok->text : "a number";
		case tk_string:	return tok ? ("\"" + tok->text + "\"") : "a string";
		case tk_any:	return tok ? tok->text : "any token";
		default: break;
	}

	return "";
}

// =============================================================================
//
bool lexer::peek_next (lexer::token* tk)
{
	iterator pos = m_token_position;
	bool r = get_next();

	if (r && tk != null)
		*tk = *m_token_position;

	m_token_position = pos;
	return r;
}

// =============================================================================
//
lexer* lexer::get_main_lexer()
{
	return g_main_lexer;
}

// =============================================================================
//
string lexer::peek_next_string (int a)
{
	if (m_token_position + a >= m_tokens.end())
		return "";

	iterator oldpos = m_token_position;
	m_token_position += a;
	string result = get_token()->text;
	m_token_position = oldpos;
	return result;
}