sh: Import arithmetic expression code from dash.

New features:
* proper lazy evaluation of || and &&
* ?: ternary operator
* executable is considerably smaller (8K on i386) because lex and yacc are
  no longer used

Differences from dash:
* arith_t instead of intmax_t
* imaxdiv() not used
* unset or null variables default to 0
* let/exp builtin (undocumented, will probably be removed later)

Obtained from:	dash

1 files changed, 244 insertions, 0 deletions

diff --git a/bin/sh/arith_yylex.c b/bin/sh/arith_yylex.c
new file mode 100644
index 0000000..0d08a83
--- /dev/null
+++ b/bin/sh/arith_yylex.c
@@ -0,0 +1,244 @@
+/*-
+ * Copyright (c) 2002
+ *	Herbert Xu.
+ * Copyright (c) 1993
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * This code is derived from software contributed to Berkeley by
+ * Kenneth Almquist.
+ *
+ * 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. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <inttypes.h>
+#include <stdlib.h>
+#include <string.h>
+#include "shell.h"
+#include "arith_yacc.h"
+#include "expand.h"
+#include "error.h"
+#include "memalloc.h"
+#include "parser.h"
+#include "syntax.h"
+
+#if ARITH_BOR + 11 != ARITH_BORASS || ARITH_ASS + 11 != ARITH_EQ
+#error Arithmetic tokens are out of order.
+#endif
+
+extern const char *arith_buf;
+
+int
+yylex()
+{
+	int value;
+	const char *buf = arith_buf;
+	const char *p;
+
+	for (;;) {
+		value = *buf;
+		switch (value) {
+		case ' ':
+		case '\t':
+		case '\n':
+			buf++;
+			continue;
+		default:
+			return ARITH_BAD;
+		case '0':
+		case '1':
+		case '2':
+		case '3':
+		case '4':
+		case '5':
+		case '6':
+		case '7':
+		case '8':
+		case '9':
+			yylval.val = strtoarith_t(buf, (char **)&arith_buf, 0);
+			return ARITH_NUM;
+		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':
+		case '_':
+		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':
+			p = buf;
+			while (buf++, is_in_name(*buf))
+				;
+			yylval.name = stalloc(buf - p + 1);
+			memcpy(yylval.name, p, buf - p);
+			yylval.name[buf - p] = '\0';
+			value = ARITH_VAR;
+			goto out;
+		case '=':
+			value += ARITH_ASS - '=';
+checkeq:
+			buf++;
+checkeqcur:
+			if (*buf != '=')
+				goto out;
+			value += 11;
+			break;
+		case '>':
+			switch (*++buf) {
+			case '=':
+				value += ARITH_GE - '>';
+				break;
+			case '>':
+				value += ARITH_RSHIFT - '>';
+				goto checkeq;
+			default:
+				value += ARITH_GT - '>';
+				goto out;
+			}
+			break;
+		case '<':
+			switch (*++buf) {
+			case '=':
+				value += ARITH_LE - '<';
+				break;
+			case '<':
+				value += ARITH_LSHIFT - '<';
+				goto checkeq;
+			default:
+				value += ARITH_LT - '<';
+				goto out;
+			}
+			break;
+		case '|':
+			if (*++buf != '|') {
+				value += ARITH_BOR - '|';
+				goto checkeqcur;
+			}
+			value += ARITH_OR - '|';
+			break;
+		case '&':
+			if (*++buf != '&') {
+				value += ARITH_BAND - '&';
+				goto checkeqcur;
+			}
+			value += ARITH_AND - '&';
+			break;
+		case '!':
+			if (*++buf != '=') {
+				value += ARITH_NOT - '!';
+				goto out;
+			}
+			value += ARITH_NE - '!';
+			break;
+		case 0:
+			goto out;
+		case '(':
+			value += ARITH_LPAREN - '(';
+			break;
+		case ')':
+			value += ARITH_RPAREN - ')';
+			break;
+		case '*':
+			value += ARITH_MUL - '*';
+			goto checkeq;
+		case '/':
+			value += ARITH_DIV - '/';
+			goto checkeq;
+		case '%':
+			value += ARITH_REM - '%';
+			goto checkeq;
+		case '+':
+			value += ARITH_ADD - '+';
+			goto checkeq;
+		case '-':
+			value += ARITH_SUB - '-';
+			goto checkeq;
+		case '~':
+			value += ARITH_BNOT - '~';
+			break;
+		case '^':
+			value += ARITH_BXOR - '^';
+			goto checkeq;
+		case '?':
+			value += ARITH_QMARK - '?';
+			break;
+		case ':':
+			value += ARITH_COLON - ':';
+			break;
+		}
+		break;
+	}
+
+	buf++;
+out:
+	arith_buf = buf;
+	return value;
+}