src/bc_lex.c - platform/external/bc - Git at Google

 /*
  * *****************************************************************************
  *
  * SPDX-License-Identifier: BSD-2-Clause
  *
  * Copyright (c) 2018-2021 Gavin D. Howard and contributors.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
  *
  * * Redistributions of source code must retain the above copyright notice, this
  *   list of conditions and the following disclaimer.
  *
  * * 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.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 COPYRIGHT HOLDER OR CONTRIBUTORS 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.
  *
  * *****************************************************************************
  *
  * The lexer for bc.
  *
  */

 #if BC_ENABLED

 #include <assert.h>
 #include <ctype.h>
 #include <string.h>

 #include <bc.h>
 #include <vm.h>

 /**
  * Lexes an identifier, which may be a keyword.
  * @param l  The lexer.
  */
 static void bc_lex_identifier(BcLex *l) {

 	// We already passed the first character, so we need to be sure to include
 	// it.
 	const char *buf = l->buf + l->i - 1;
 	size_t i;

 	// This loop is simply checking for keywords.
 	for (i = 0; i < bc_lex_kws_len; ++i) {

 		const BcLexKeyword *kw = bc_lex_kws + i;
 		size_t n = BC_LEX_KW_LEN(kw);

 		if (!strncmp(buf, kw->name, n) && !isalnum(buf[n]) && buf[n] != '_') {

 			// If the keyword has been redefined, and redefinition is allowed
 			// (it is not allowed for builtin libraries), break out of the loop
 			// and use it as a name. This depends on the argument parser to
 			// ensure that only non-POSIX keywords get redefined.
 			if (!vm.no_redefine && vm.redefined_kws[i]) break;

 			l->t = BC_LEX_KW_AUTO + (BcLexType) i;

 			// Warn or error, as appropriate for the mode, if the keyword is not
 			// in the POSIX standard.
 			if (!BC_LEX_KW_POSIX(kw)) bc_lex_verr(l, BC_ERR_POSIX_KW, kw->name);

 			// We minus 1 because the index has already been incremented.
 			l->i += n - 1;

 			// Already have the token; bail.
 			return;
 		}
 	}

 	// If not a keyword, parse the name.
 	bc_lex_name(l);

 	// POSIX doesn't allow identifiers that are more than one character, so we
 	// might have to warn or error here too.
 	if (BC_ERR(l->str.len - 1 > 1))
 		bc_lex_verr(l, BC_ERR_POSIX_NAME_LEN, l->str.v);
 }

 /**
  * Parses a bc string. This is separate from dc strings because dc strings need
  * to be balanced.
  * @param l  The lexer.
  */
 static void bc_lex_string(BcLex *l) {

 	// We need to keep track of newlines to increment them properly.
 	size_t len, nlines, i;
 	const char *buf;
 	char c;
 	bool got_more;

 	l->t = BC_LEX_STR;

 	do {

 		nlines = 0;
 		buf = l->buf;
 		got_more = false;

 		assert(!vm.is_stdin || buf == vm.buffer.v);

 		// Fortunately for us, bc doesn't escape quotes. Instead, the equivalent
 		// is '\q', which makes this loop simpler.
 		for (i = l->i; (c = buf[i]) && c != '"'; ++i) nlines += (c == '\n');

 		if (BC_ERR(c == '\0') && !vm.eof && l->is_stdin)
 			got_more = bc_lex_readLine(l);

 	} while (got_more && c != '"');

 	// If the string did not end properly, barf.
 	if (c != '"') {
 		l->i = i;
 		bc_lex_err(l, BC_ERR_PARSE_STRING);
 	}

 	// Set the temp string to the parsed string.
 	len = i - l->i;
 	bc_vec_string(&l->str, len, l->buf + l->i);

 	l->i = i + 1;
 	l->line += nlines;
 }

 /**
  * This function takes a lexed operator and checks to see if it's the assignment
  * version, setting the token appropriately.
  * @param l        The lexer.
  * @param with     The token to assign if it is an assignment operator.
  * @param without  The token to assign if it is not an assignment operator.
  */
 static void bc_lex_assign(BcLex *l, BcLexType with, BcLexType without) {
 	if (l->buf[l->i] == '=') {
 		l->i += 1;
 		l->t = with;
 	}
 	else l->t = without;
 }

 void bc_lex_token(BcLex *l) {

 	// We increment here. This means that all lexing needs to take that into
 	// account, such as when parsing an identifier. If we don't, the first
 	// character of every identifier would be missing.
 	char c = l->buf[l->i++], c2;

 	// This is the workhorse of the lexer.
 	switch (c) {

 		case '\0':
 		case '\n':
 		case '\t':
 		case '\v':
 		case '\f':
 		case '\r':
 		case ' ':
 		{
 			bc_lex_commonTokens(l, c);
 			break;
 		}

 		case '!':
 		{
 			// Even though it's not an assignment, we can use this.
 			bc_lex_assign(l, BC_LEX_OP_REL_NE, BC_LEX_OP_BOOL_NOT);

 			// POSIX doesn't allow boolean not.
 			if (l->t == BC_LEX_OP_BOOL_NOT)
 				bc_lex_verr(l, BC_ERR_POSIX_BOOL, "!");

 			break;
 		}

 		case '"':
 		{
 			bc_lex_string(l);
 			break;
 		}

 		case '#':
 		{
 			// POSIX does not allow line comments.
 			bc_lex_err(l, BC_ERR_POSIX_COMMENT);
 			bc_lex_lineComment(l);
 			break;
 		}

 		case '%':
 		{
 			bc_lex_assign(l, BC_LEX_OP_ASSIGN_MODULUS, BC_LEX_OP_MODULUS);
 			break;
 		}

 		case '&':
 		{
 			c2 = l->buf[l->i];

 			// Either we have boolean and or an error. And boolean and is not
 			// allowed by POSIX.
 			if (BC_NO_ERR(c2 == '&')) {

 				bc_lex_verr(l, BC_ERR_POSIX_BOOL, "&&");

 				l->i += 1;
 				l->t = BC_LEX_OP_BOOL_AND;
 			}
 			else bc_lex_invalidChar(l, c);

 			break;
 		}
 #if BC_ENABLE_EXTRA_MATH
 		case '$':
 		{
 			l->t = BC_LEX_OP_TRUNC;
 			break;
 		}

 		case '@':
 		{
 			bc_lex_assign(l, BC_LEX_OP_ASSIGN_PLACES, BC_LEX_OP_PLACES);
 			break;
 		}
 #endif // BC_ENABLE_EXTRA_MATH
 		case '(':
 		case ')':
 		{
 			l->t = (BcLexType) (c - '(' + BC_LEX_LPAREN);
 			break;
 		}

 		case '*':
 		{
 			bc_lex_assign(l, BC_LEX_OP_ASSIGN_MULTIPLY, BC_LEX_OP_MULTIPLY);
 			break;
 		}

 		case '+':
 		{
 			c2 = l->buf[l->i];

 			// Have to check for increment first.
 			if (c2 == '+') {
 				l->i += 1;
 				l->t = BC_LEX_OP_INC;
 			}
 			else bc_lex_assign(l, BC_LEX_OP_ASSIGN_PLUS, BC_LEX_OP_PLUS);
 			break;
 		}

 		case ',':
 		{
 			l->t = BC_LEX_COMMA;
 			break;
 		}

 		case '-':
 		{
 			c2 = l->buf[l->i];

 			// Have to check for decrement first.
 			if (c2 == '-') {
 				l->i += 1;
 				l->t = BC_LEX_OP_DEC;
 			}
 			else bc_lex_assign(l, BC_LEX_OP_ASSIGN_MINUS, BC_LEX_OP_MINUS);
 			break;
 		}

 		case '.':
 		{
 			c2 = l->buf[l->i];

 			// If it's alone, it's an alias for last.
 			if (BC_LEX_NUM_CHAR(c2, true, false)) bc_lex_number(l, c);
 			else {
 				l->t = BC_LEX_KW_LAST;
 				bc_lex_err(l, BC_ERR_POSIX_DOT);
 			}

 			break;
 		}

 		case '/':
 		{
 			c2 = l->buf[l->i];
 			if (c2 =='*') bc_lex_comment(l);
 			else bc_lex_assign(l, BC_LEX_OP_ASSIGN_DIVIDE, BC_LEX_OP_DIVIDE);
 			break;
 		}

 		case '0':
 		case '1':
 		case '2':
 		case '3':
 		case '4':
 		case '5':
 		case '6':
 		case '7':
 		case '8':
 		case '9':
 		case 'A':
 		case 'B':
 		case 'C':
 		case 'D':
 		case 'E':
 		case 'F':
 		// Apparently, GNU bc (and maybe others) allows any uppercase letter as
 		// a number. When single digits, they act like the ones above. When
 		// multi-digit, any letter above the input base is automatically set to
 		// the biggest allowable digit in the input base.
 		case 'G':
 		case 'H':
 		case 'I':
 		case 'J':
 		case 'K':
 		case 'L':
 		case 'M':
 		case 'N':
 		case 'O':
 		case 'P':
 		case 'Q':
 		case 'R':
 		case 'S':
 		case 'T':
 		case 'U':
 		case 'V':
 		case 'W':
 		case 'X':
 		case 'Y':
 		case 'Z':
 		{
 			bc_lex_number(l, c);
 			break;
 		}

 		case ';':
 		{
 			l->t = BC_LEX_SCOLON;
 			break;
 		}

 		case '<':
 		{
 #if BC_ENABLE_EXTRA_MATH
 			c2 = l->buf[l->i];

 			// Check for shift.
 			if (c2 == '<') {
 				l->i += 1;
 				bc_lex_assign(l, BC_LEX_OP_ASSIGN_LSHIFT, BC_LEX_OP_LSHIFT);
 				break;
 			}
 #endif // BC_ENABLE_EXTRA_MATH
 			bc_lex_assign(l, BC_LEX_OP_REL_LE, BC_LEX_OP_REL_LT);
 			break;
 		}

 		case '=':
 		{
 			bc_lex_assign(l, BC_LEX_OP_REL_EQ, BC_LEX_OP_ASSIGN);
 			break;
 		}

 		case '>':
 		{
 #if BC_ENABLE_EXTRA_MATH
 			c2 = l->buf[l->i];

 			// Check for shift.
 			if (c2 == '>') {
 				l->i += 1;
 				bc_lex_assign(l, BC_LEX_OP_ASSIGN_RSHIFT, BC_LEX_OP_RSHIFT);
 				break;
 			}
 #endif // BC_ENABLE_EXTRA_MATH
 			bc_lex_assign(l, BC_LEX_OP_REL_GE, BC_LEX_OP_REL_GT);
 			break;
 		}

 		case '[':
 		case ']':
 		{
 			l->t = (BcLexType) (c - '[' + BC_LEX_LBRACKET);
 			break;
 		}

 		case '\\':
 		{
 			// In bc, a backslash+newline is whitespace.
 			if (BC_NO_ERR(l->buf[l->i] == '\n')) {
 				l->i += 1;
 				l->t = BC_LEX_WHITESPACE;
 			}
 			else bc_lex_invalidChar(l, c);
 			break;
 		}

 		case '^':
 		{
 			bc_lex_assign(l, BC_LEX_OP_ASSIGN_POWER, BC_LEX_OP_POWER);
 			break;
 		}

 		case 'a':
 		case 'b':
 		case 'c':
 		case 'd':
 		case 'e':
 		case 'f':
 		case 'g':
 		case 'h':
 		case 'i':
 		case 'j':
 		case 'k':
 		case 'l':
 		case 'm':
 		case 'n':
 		case 'o':
 		case 'p':
 		case 'q':
 		case 'r':
 		case 's':
 		case 't':
 		case 'u':
 		case 'v':
 		case 'w':
 		case 'x':
 		case 'y':
 		case 'z':
 		{
 			bc_lex_identifier(l);
 			break;
 		}

 		case '{':
 		case '}':
 		{
 			l->t = (BcLexType) (c - '{' + BC_LEX_LBRACE);
 			break;
 		}

 		case '|':
 		{
 			c2 = l->buf[l->i];

 			// Once again, boolean or is not allowed by POSIX.
 			if (BC_NO_ERR(c2 == '|')) {

 				bc_lex_verr(l, BC_ERR_POSIX_BOOL, "||");

 				l->i += 1;
 				l->t = BC_LEX_OP_BOOL_OR;
 			}
 			else bc_lex_invalidChar(l, c);

 			break;
 		}

 		default:
 		{
 			bc_lex_invalidChar(l, c);
 		}
 	}
 }
 #endif // BC_ENABLED
	/*
	* *****************************************************************************
	*
	* SPDX-License-Identifier: BSD-2-Clause
	*
	* Copyright (c) 2018-2021 Gavin D. Howard and contributors.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions are met:
	*
	* * Redistributions of source code must retain the above copyright notice, this
	* list of conditions and the following disclaimer.
	*
	* * 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.
	*
	* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 COPYRIGHT HOLDER OR CONTRIBUTORS 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.
	*
	* *****************************************************************************
	*
	* The lexer for bc.
	*
	*/

	#if BC_ENABLED

	#include <assert.h>
	#include <ctype.h>
	#include <string.h>

	#include <bc.h>
	#include <vm.h>

	/**
	* Lexes an identifier, which may be a keyword.
	* @param l The lexer.
	*/
	static void bc_lex_identifier(BcLex *l) {

	// We already passed the first character, so we need to be sure to include
	// it.
	const char *buf = l->buf + l->i - 1;
	size_t i;

	// This loop is simply checking for keywords.
	for (i = 0; i < bc_lex_kws_len; ++i) {

	const BcLexKeyword *kw = bc_lex_kws + i;
	size_t n = BC_LEX_KW_LEN(kw);

	if (!strncmp(buf, kw->name, n) && !isalnum(buf[n]) && buf[n] != '_') {

	// If the keyword has been redefined, and redefinition is allowed
	// (it is not allowed for builtin libraries), break out of the loop
	// and use it as a name. This depends on the argument parser to
	// ensure that only non-POSIX keywords get redefined.
	if (!vm.no_redefine && vm.redefined_kws[i]) break;

	l->t = BC_LEX_KW_AUTO + (BcLexType) i;

	// Warn or error, as appropriate for the mode, if the keyword is not
	// in the POSIX standard.
	if (!BC_LEX_KW_POSIX(kw)) bc_lex_verr(l, BC_ERR_POSIX_KW, kw->name);

	// We minus 1 because the index has already been incremented.
	l->i += n - 1;

	// Already have the token; bail.
	return;
	}
	}

	// If not a keyword, parse the name.
	bc_lex_name(l);

	// POSIX doesn't allow identifiers that are more than one character, so we
	// might have to warn or error here too.
	if (BC_ERR(l->str.len - 1 > 1))
	bc_lex_verr(l, BC_ERR_POSIX_NAME_LEN, l->str.v);
	}

	/**
	* Parses a bc string. This is separate from dc strings because dc strings need
	* to be balanced.
	* @param l The lexer.
	*/
	static void bc_lex_string(BcLex *l) {

	// We need to keep track of newlines to increment them properly.
	size_t len, nlines, i;
	const char *buf;
	char c;
	bool got_more;

	l->t = BC_LEX_STR;

	do {

	nlines = 0;
	buf = l->buf;
	got_more = false;

	assert(!vm.is_stdin \|\| buf == vm.buffer.v);

	// Fortunately for us, bc doesn't escape quotes. Instead, the equivalent
	// is '\q', which makes this loop simpler.
	for (i = l->i; (c = buf[i]) && c != '"'; ++i) nlines += (c == '\n');

	if (BC_ERR(c == '\0') && !vm.eof && l->is_stdin)
	got_more = bc_lex_readLine(l);

	} while (got_more && c != '"');

	// If the string did not end properly, barf.
	if (c != '"') {
	l->i = i;
	bc_lex_err(l, BC_ERR_PARSE_STRING);
	}

	// Set the temp string to the parsed string.
	len = i - l->i;
	bc_vec_string(&l->str, len, l->buf + l->i);

	l->i = i + 1;
	l->line += nlines;
	}

	/**
	* This function takes a lexed operator and checks to see if it's the assignment
	* version, setting the token appropriately.
	* @param l The lexer.
	* @param with The token to assign if it is an assignment operator.
	* @param without The token to assign if it is not an assignment operator.
	*/
	static void bc_lex_assign(BcLex *l, BcLexType with, BcLexType without) {
	if (l->buf[l->i] == '=') {
	l->i += 1;
	l->t = with;
	}
	else l->t = without;
	}

	void bc_lex_token(BcLex *l) {

	// We increment here. This means that all lexing needs to take that into
	// account, such as when parsing an identifier. If we don't, the first
	// character of every identifier would be missing.
	char c = l->buf[l->i++], c2;

	// This is the workhorse of the lexer.
	switch (c) {

	case '\0':
	case '\n':
	case '\t':
	case '\v':
	case '\f':
	case '\r':
	case ' ':
	{
	bc_lex_commonTokens(l, c);
	break;
	}

	case '!':
	{
	// Even though it's not an assignment, we can use this.
	bc_lex_assign(l, BC_LEX_OP_REL_NE, BC_LEX_OP_BOOL_NOT);

	// POSIX doesn't allow boolean not.
	if (l->t == BC_LEX_OP_BOOL_NOT)
	bc_lex_verr(l, BC_ERR_POSIX_BOOL, "!");

	break;
	}

	case '"':
	{
	bc_lex_string(l);
	break;
	}

	case '#':
	{
	// POSIX does not allow line comments.
	bc_lex_err(l, BC_ERR_POSIX_COMMENT);
	bc_lex_lineComment(l);
	break;
	}

	case '%':
	{
	bc_lex_assign(l, BC_LEX_OP_ASSIGN_MODULUS, BC_LEX_OP_MODULUS);
	break;
	}

	case '&':
	{
	c2 = l->buf[l->i];

	// Either we have boolean and or an error. And boolean and is not
	// allowed by POSIX.
	if (BC_NO_ERR(c2 == '&')) {

	bc_lex_verr(l, BC_ERR_POSIX_BOOL, "&&");

	l->i += 1;
	l->t = BC_LEX_OP_BOOL_AND;
	}
	else bc_lex_invalidChar(l, c);

	break;
	}
	#if BC_ENABLE_EXTRA_MATH
	case '$':
	{
	l->t = BC_LEX_OP_TRUNC;
	break;
	}

	case '@':
	{
	bc_lex_assign(l, BC_LEX_OP_ASSIGN_PLACES, BC_LEX_OP_PLACES);
	break;
	}
	#endif // BC_ENABLE_EXTRA_MATH
	case '(':
	case ')':
	{
	l->t = (BcLexType) (c - '(' + BC_LEX_LPAREN);
	break;
	}

	case '*':
	{
	bc_lex_assign(l, BC_LEX_OP_ASSIGN_MULTIPLY, BC_LEX_OP_MULTIPLY);
	break;
	}

	case '+':
	{
	c2 = l->buf[l->i];

	// Have to check for increment first.
	if (c2 == '+') {
	l->i += 1;
	l->t = BC_LEX_OP_INC;
	}
	else bc_lex_assign(l, BC_LEX_OP_ASSIGN_PLUS, BC_LEX_OP_PLUS);
	break;
	}

	case ',':
	{
	l->t = BC_LEX_COMMA;
	break;
	}

	case '-':
	{
	c2 = l->buf[l->i];

	// Have to check for decrement first.
	if (c2 == '-') {
	l->i += 1;
	l->t = BC_LEX_OP_DEC;
	}
	else bc_lex_assign(l, BC_LEX_OP_ASSIGN_MINUS, BC_LEX_OP_MINUS);
	break;
	}

	case '.':
	{
	c2 = l->buf[l->i];

	// If it's alone, it's an alias for last.
	if (BC_LEX_NUM_CHAR(c2, true, false)) bc_lex_number(l, c);
	else {
	l->t = BC_LEX_KW_LAST;
	bc_lex_err(l, BC_ERR_POSIX_DOT);
	}

	break;
	}

	case '/':
	{
	c2 = l->buf[l->i];
	if (c2 =='*') bc_lex_comment(l);
	else bc_lex_assign(l, BC_LEX_OP_ASSIGN_DIVIDE, BC_LEX_OP_DIVIDE);
	break;
	}

	case '0':
	case '1':
	case '2':
	case '3':
	case '4':
	case '5':
	case '6':
	case '7':
	case '8':
	case '9':
	case 'A':
	case 'B':
	case 'C':
	case 'D':
	case 'E':
	case 'F':
	// Apparently, GNU bc (and maybe others) allows any uppercase letter as
	// a number. When single digits, they act like the ones above. When
	// multi-digit, any letter above the input base is automatically set to
	// the biggest allowable digit in the input base.
	case 'G':
	case 'H':
	case 'I':
	case 'J':
	case 'K':
	case 'L':
	case 'M':
	case 'N':
	case 'O':
	case 'P':
	case 'Q':
	case 'R':
	case 'S':
	case 'T':
	case 'U':
	case 'V':
	case 'W':
	case 'X':
	case 'Y':
	case 'Z':
	{
	bc_lex_number(l, c);
	break;
	}

	case ';':
	{
	l->t = BC_LEX_SCOLON;
	break;
	}

	case '<':
	{
	#if BC_ENABLE_EXTRA_MATH
	c2 = l->buf[l->i];

	// Check for shift.
	if (c2 == '<') {
	l->i += 1;
	bc_lex_assign(l, BC_LEX_OP_ASSIGN_LSHIFT, BC_LEX_OP_LSHIFT);
	break;
	}
	#endif // BC_ENABLE_EXTRA_MATH
	bc_lex_assign(l, BC_LEX_OP_REL_LE, BC_LEX_OP_REL_LT);
	break;
	}

	case '=':
	{
	bc_lex_assign(l, BC_LEX_OP_REL_EQ, BC_LEX_OP_ASSIGN);
	break;
	}

	case '>':
	{
	#if BC_ENABLE_EXTRA_MATH
	c2 = l->buf[l->i];

	// Check for shift.
	if (c2 == '>') {
	l->i += 1;
	bc_lex_assign(l, BC_LEX_OP_ASSIGN_RSHIFT, BC_LEX_OP_RSHIFT);
	break;
	}
	#endif // BC_ENABLE_EXTRA_MATH
	bc_lex_assign(l, BC_LEX_OP_REL_GE, BC_LEX_OP_REL_GT);
	break;
	}

	case '[':
	case ']':
	{
	l->t = (BcLexType) (c - '[' + BC_LEX_LBRACKET);
	break;
	}

	case '\\':
	{
	// In bc, a backslash+newline is whitespace.
	if (BC_NO_ERR(l->buf[l->i] == '\n')) {
	l->i += 1;
	l->t = BC_LEX_WHITESPACE;
	}
	else bc_lex_invalidChar(l, c);
	break;
	}

	case '^':
	{
	bc_lex_assign(l, BC_LEX_OP_ASSIGN_POWER, BC_LEX_OP_POWER);
	break;
	}

	case 'a':
	case 'b':
	case 'c':
	case 'd':
	case 'e':
	case 'f':
	case 'g':
	case 'h':
	case 'i':
	case 'j':
	case 'k':
	case 'l':
	case 'm':
	case 'n':
	case 'o':
	case 'p':
	case 'q':
	case 'r':
	case 's':
	case 't':
	case 'u':
	case 'v':
	case 'w':
	case 'x':
	case 'y':
	case 'z':
	{
	bc_lex_identifier(l);
	break;
	}

	case '{':
	case '}':
	{
	l->t = (BcLexType) (c - '{' + BC_LEX_LBRACE);
	break;
	}

	case '\|':
	{
	c2 = l->buf[l->i];

	// Once again, boolean or is not allowed by POSIX.
	if (BC_NO_ERR(c2 == '\|')) {

	bc_lex_verr(l, BC_ERR_POSIX_BOOL, "\|\|");

	l->i += 1;
	l->t = BC_LEX_OP_BOOL_OR;
	}
	else bc_lex_invalidChar(l, c);

	break;
	}

	default:
	{
	bc_lex_invalidChar(l, c);
	}
	}
	}
	#endif // BC_ENABLED