An implementation of Unix dc and POSIX bc with GNU and BSD extensions. Finished, but well-maintained.
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/*
* *****************************************************************************
*
* 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 dc.
*
*/
#if DC_ENABLED
#include <ctype.h>
#include <dc.h>
#include <vm.h>
bool
dc_lex_negCommand(BcLex* l)
{
char c = l->buf[l->i];
return !BC_LEX_NUM_CHAR(c, false, false);
}
/**
* Processes a dc command that needs a register. This is where the
* extended-register extension is implemented.
* @param l The lexer.
*/
static void
dc_lex_register(BcLex* l)
{
// If extended register is enabled and the character is whitespace...
if (DC_X && isspace(l->buf[l->i - 1]))
{
char c;
// Eat the whitespace.
bc_lex_whitespace(l);
c = l->buf[l->i];
// Check for a letter or underscore.
if (BC_ERR(!isalpha(c) && c != '_'))
{
bc_lex_verr(l, BC_ERR_PARSE_CHAR, c);
}
// Parse a normal identifier.
l->i += 1;
bc_lex_name(l);
}
else
{
// I don't allow newlines because newlines are used for controlling when
// execution happens, and allowing newlines would just be complex.
if (BC_ERR(l->buf[l->i - 1] == '\n'))
{
bc_lex_verr(l, BC_ERR_PARSE_CHAR, l->buf[l->i - 1]);
}
// Set the lexer string and token.
bc_vec_popAll(&l->str);
bc_vec_pushByte(&l->str, (uchar) l->buf[l->i - 1]);
bc_vec_pushByte(&l->str, '\0');
l->t = BC_LEX_NAME;
}
}
/**
* Parses a dc string. Since dc's strings need to check for balanced brackets,
* we can't just parse bc and dc strings with different start and end
* characters. Oh, and dc strings need to check for escaped brackets.
* @param l The lexer.
*/
static void
dc_lex_string(BcLex* l)
{
size_t depth, nls, i;
char c;
bool got_more;
// Set the token and clear the string.
l->t = BC_LEX_STR;
bc_vec_popAll(&l->str);
do
{
depth = 1;
nls = 0;
got_more = false;
assert(!l->is_stdin || l->buf == vm->buffer.v);
// This is the meat. As long as we don't run into the NUL byte, and we
// have "depth", which means we haven't completely balanced brackets
// yet, we continue eating the string.
for (i = l->i; (c = l->buf[i]) && depth; ++i)
{
// Check for escaped brackets and set the depths as appropriate.
if (c == '\\')
{
c = l->buf[++i];
if (!c) break;
}
else
{
depth += (c == '[');
depth -= (c == ']');
}
// We want to adjust the line in the lexer as necessary.
nls += (c == '\n');
if (depth) bc_vec_push(&l->str, &c);
}
if (BC_ERR(c == '\0' && depth))
{
if (!vm->eof && (l->is_stdin || l->is_exprs))
{
got_more = bc_lex_readLine(l);
}
if (got_more) bc_vec_popAll(&l->str);
}
}
while (got_more && depth);
// Obviously, if we didn't balance, that's an error.
if (BC_ERR(c == '\0' && depth))
{
l->i = i;
bc_lex_err(l, BC_ERR_PARSE_STRING);
}
bc_vec_pushByte(&l->str, '\0');
l->i = i;
l->line += nls;
}
/**
* Lexes a dc token. This is the dc implementation of BcLexNext.
* @param l The lexer.
*/
void
dc_lex_token(BcLex* l)
{
char c = l->buf[l->i++], c2;
size_t i;
BC_SIG_ASSERT_LOCKED;
// If the last token was a command that needs a register, we need to parse a
// register, so do so.
for (i = 0; i < dc_lex_regs_len; ++i)
{
// If the token is a register token, take care of it and return.
if (l->last == dc_lex_regs[i])
{
dc_lex_register(l);
return;
}
}
// These lines are for tokens that easily correspond to one character. We
// just set the token.
if (c >= '"' && c <= '~' &&
(l->t = dc_lex_tokens[(c - '"')]) != BC_LEX_INVALID)
{
return;
}
// This is the workhorse of the lexer when more complicated things are
// needed.
switch (c)
{
case '\0':
case '\n':
case '\t':
case '\v':
case '\f':
case '\r':
case ' ':
{
bc_lex_commonTokens(l, c);
break;
}
// We don't have the ! command, so we always expect certain things
// after the exclamation point.
case '!':
{
c2 = l->buf[l->i];
if (c2 == '=') l->t = BC_LEX_OP_REL_NE;
else if (c2 == '<') l->t = BC_LEX_OP_REL_LE;
else if (c2 == '>') l->t = BC_LEX_OP_REL_GE;
else bc_lex_invalidChar(l, c);
l->i += 1;
break;
}
case '#':
{
bc_lex_lineComment(l);
break;
}
case '.':
{
c2 = l->buf[l->i];
// If the character after is a number, this dot is part of a number.
// Otherwise, it's the BSD dot (equivalent to last).
if (BC_NO_ERR(BC_LEX_NUM_CHAR(c2, true, false)))
{
bc_lex_number(l, c);
}
else bc_lex_invalidChar(l, c);
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':
{
bc_lex_number(l, c);
break;
}
case 'g':
{
c2 = l->buf[l->i];
if (c2 == 'l') l->t = BC_LEX_KW_LINE_LENGTH;
else if (c2 == 'z') l->t = BC_LEX_KW_LEADING_ZERO;
else bc_lex_invalidChar(l, c2);
l->i += 1;
break;
}
case '[':
{
dc_lex_string(l);
break;
}
default:
{
bc_lex_invalidChar(l, c);
}
}
}
#endif // DC_ENABLED