--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/eval.c	Mon Dec 20 00:32:20 2010 -0500
@@ -0,0 +1,669 @@
+#include <stdlib.h>
+#include <string.h>
+#include <limits.h>
+#include <errno.h>
+
+#include "utils.h"
+#include "array.h"
+#include "mode.h"
+#include "place.h"
+#include "eval.h"
+
+/*
+ * e ::=
+ *    e1 ? e2 : e3
+ *    e1 || e2
+ *    e1 && e2
+ *    e1 | e2
+ *    e1 ^ e2
+ *    e1 & e2
+ *    e1 == e2  |  e1 != e2
+ *    e1 < e2   |  e1 <= e2  |  e1 > e2  |  e1 >= e2
+ *    e1 << e2  |  e1 >> e2
+ *    e1 + e2   |  e1 - e2
+ *    e1 * e2   |  e1 / e2   |  e1 % e2
+ *    !e  |  ~e  |  -e  |  +e
+ *    ( e )  |  ident
+ */
+
+enum tokens {
+	T_EOF,		/* end of input */
+	T_VAL,		/* value */
+	T_LPAREN,	/* parens */
+	T_RPAREN,
+	T_PIPEPIPE,	/* operators */
+	T_AMPAMP,
+	T_EQEQ,
+	T_BANGEQ,
+	T_LTEQ,
+	T_GTEQ,
+	T_LTLT,
+	T_GTGT,
+	T_QUES,
+	T_COLON,
+	T_PIPE,
+	T_CARET,
+	T_AMP,
+	T_LT,
+	T_GT,
+	T_PLUS,
+	T_MINUS,
+	T_STAR,
+	T_SLASH,
+	T_PCT,
+	T_BANG,
+	T_TILDE,
+};
+
+static const struct {
+	char c1, c2;
+	enum tokens tok;
+} tokens_2[] = {
+	{ '|', '|', T_PIPEPIPE },
+	{ '&', '&', T_AMPAMP },
+	{ '=', '=', T_EQEQ },
+	{ '!', '=', T_BANGEQ },
+	{ '<', '=', T_LTEQ },
+	{ '>', '=', T_GTEQ },
+	{ '<', '<', T_LTLT },
+	{ '>', '>', T_GTGT },
+};
+static const unsigned num_tokens_2 = HOWMANY(tokens_2);
+
+static const struct {
+	char c1;
+	enum tokens tok;
+} tokens_1[] = {
+	{ '?', T_QUES },
+	{ ':', T_COLON },
+	{ '|', T_PIPE },
+	{ '^', T_CARET },
+	{ '&', T_AMP },
+	{ '<', T_LT },
+	{ '>', T_GT },
+	{ '+', T_PLUS },
+	{ '-', T_MINUS },
+	{ '*', T_STAR },
+	{ '/', T_SLASH },
+	{ '%', T_PCT },
+	{ '!', T_BANG },
+	{ '~', T_TILDE },
+	{ '(', T_LPAREN },
+	{ ')', T_RPAREN },
+};
+static const unsigned num_tokens_1 = HOWMANY(tokens_1);
+
+struct token {
+	struct place place;
+	enum tokens tok;
+	int val;
+};
+DECLARRAY(token);
+DEFARRAY(token, );
+
+static struct tokenarray tokens;
+
+static
+struct token *
+token_create(const struct place *p, enum tokens tok, int val)
+{
+	struct token *t;
+
+	t = domalloc(sizeof(*t));
+	t->place = *p;
+	t->tok = tok;
+	t->val = val;
+	return t;
+}
+
+static
+void
+token_destroy(struct token *t)
+{
+	free(t);
+}
+
+DESTROYALL_ARRAY(token, );
+
+static
+bool
+isuop(enum tokens tok)
+{
+	switch (tok) {
+	    case T_BANG:
+	    case T_TILDE:
+	    case T_MINUS:
+	    case T_PLUS:
+		return true;
+	    default:
+		break;
+	}
+	return false;
+}
+
+static
+bool
+isbop(enum tokens tok)
+{
+	switch (tok) {
+	    case T_EOF:
+	    case T_VAL:
+	    case T_LPAREN:
+	    case T_RPAREN:
+	    case T_COLON:
+	    case T_QUES:
+	    case T_BANG:
+	    case T_TILDE:
+		return false;
+	    default:
+		break;
+	}
+	return true;
+}
+
+static
+bool
+isop(enum tokens tok)
+{
+	switch (tok) {
+	    case T_EOF:
+	    case T_VAL:
+	    case T_LPAREN:
+	    case T_RPAREN:
+		return false;
+	    default:
+		break;
+	}
+	return true;
+}
+
+static
+int
+getprec(enum tokens tok)
+{
+	switch (tok) {
+	    case T_STAR: case T_SLASH: case T_PCT: return 0;
+	    case T_PLUS: case T_MINUS: return 1;
+	    case T_LTLT: case T_GTGT: return 2;
+	    case T_LT: case T_LTEQ: case T_GT: case T_GTEQ: return 3;
+	    case T_EQEQ: case T_BANGEQ: return 4;
+	    case T_AMP: return 5;
+	    case T_CARET: return 6;
+	    case T_PIPE: return 7;
+	    case T_AMPAMP: return 8;
+	    case T_PIPEPIPE: return 9;
+	    default: break;
+	}
+	return 10;
+}
+
+static
+bool
+looser(enum tokens t1, enum tokens t2)
+{
+	return getprec(t1) > getprec(t2);
+}
+
+static
+int
+eval_uop(enum tokens op, int val)
+{
+	switch (op) {
+	    case T_BANG: val = !val; break;
+	    case T_TILDE: val = (int)~(unsigned)val; break;
+	    case T_MINUS: val = -val; break;
+	    case T_PLUS: break;
+	    default: assert(0); break;
+	}
+	return val;
+}
+
+static
+int
+eval_bop(struct place *p, enum tokens op, int lv, int rv)
+{
+	unsigned mask;
+
+	switch (op) {
+	    case T_PIPEPIPE: return lv || rv;
+	    case T_AMPAMP:   return lv && rv;
+	    case T_PIPE:     return (int)((unsigned)lv | (unsigned)rv);
+	    case T_CARET:    return (int)((unsigned)lv ^ (unsigned)rv);
+	    case T_AMP:      return (int)((unsigned)lv & (unsigned)rv);
+	    case T_EQEQ:     return lv == rv;
+	    case T_BANGEQ:   return lv != rv;
+	    case T_LT:       return lv < rv;
+	    case T_GT:       return lv > rv;
+	    case T_LTEQ:     return lv <= rv;
+	    case T_GTEQ:     return lv >= rv;
+
+	    case T_LTLT:
+	    case T_GTGT:
+		if (rv < 0) {
+			complain(p, "Negative bit-shift");
+			complain_fail();
+			rv = 0;
+		}
+		if ((unsigned)rv >= CHAR_BIT * sizeof(unsigned)) {
+			complain(p, "Bit-shift farther than type width");
+			complain_fail();
+			rv = 0;
+		}
+		if (op == T_LTLT) {
+			return (int)((unsigned)lv << (unsigned)rv);
+		}
+		mask = ((unsigned)-1) << (CHAR_BIT * sizeof(unsigned) - rv);
+		lv = (int)(((unsigned)lv >> (unsigned)rv) | mask);
+		return lv;
+
+	    case T_MINUS:
+		if (rv == INT_MIN) {
+			if (lv == INT_MIN) {
+				return 0;
+			}
+			lv--;
+			rv++;
+		}
+		rv = -rv;
+		/* FALLTHROUGH */
+	    case T_PLUS:
+		if (rv > 0 && lv > (INT_MAX - rv)) {
+			complain(p, "Integer overflow");
+			complain_fail();
+			return INT_MAX;
+		}
+		if (rv < 0 && lv < (INT_MIN - rv)) {
+			complain(p, "Integer underflow");
+			complain_fail();
+			return INT_MIN;
+		}
+		return lv + rv;
+
+	    case T_STAR:
+		if (rv == 0) {
+			return 0;
+		}
+		if (rv == 1) {
+			return lv;
+		}
+		if (rv == -1 && lv == INT_MIN) {
+			lv++;
+			lv = -lv;
+			if (lv == INT_MAX) {
+				complain(p, "Integer overflow");
+				complain_fail();
+				return INT_MAX;
+			}
+			lv++;
+			return lv;
+		}
+		if (lv == INT_MIN && rv < 0) {
+			complain(p, "Integer overflow");
+			complain_fail();
+			return INT_MAX;
+		}
+		if (lv == INT_MIN && rv > 0) {
+			complain(p, "Integer underflow");
+			complain_fail();
+			return INT_MIN;
+		}
+		if (rv < 0) {
+			rv = -rv;
+			lv = -lv;
+		}
+		if (lv > 0 && lv > INT_MAX / rv) {
+			complain(p, "Integer overflow");
+			complain_fail();
+			return INT_MAX;
+		}
+		if (lv < 0 && lv < INT_MIN / rv) {
+			complain(p, "Integer underflow");
+			complain_fail();
+			return INT_MIN;
+		}
+		return lv * rv;
+
+	    case T_SLASH:
+		if (rv == 0) {
+			complain(p, "Division by zero");
+			complain_fail();
+			return 0;
+		}
+		return lv / rv;
+
+	    case T_PCT:
+		if (rv == 0) {
+			complain(p, "Modulus by zero");
+			complain_fail();
+			return 0;
+		}
+		return lv % rv;
+
+	    default: assert(0); break;
+	}
+	return 0;
+}
+
+static
+void
+tryreduce(void)
+{
+	unsigned num;
+	struct token *t1, *t2, *t3, *t4, *t5, *t6;
+
+	while (1) {
+		num = tokenarray_num(&tokens);
+		t1 = (num >= 1) ? tokenarray_get(&tokens, num-1) : NULL;
+		t2 = (num >= 2) ? tokenarray_get(&tokens, num-2) : NULL;
+		t3 = (num >= 3) ? tokenarray_get(&tokens, num-3) : NULL;
+
+		if (num >= 3 &&
+		    t3->tok == T_LPAREN &&
+		    t2->tok == T_VAL &&
+		    t1->tok == T_RPAREN) {
+			/* (x) -> x */
+			t2->place = t3->place;
+			token_destroy(t1);
+			token_destroy(t3);
+			tokenarray_remove(&tokens, num-1);
+			tokenarray_remove(&tokens, num-3);
+			continue;
+		}
+
+		if (num >= 2 &&
+		    (num == 2 || isop(t3->tok) || t3->tok == T_LPAREN) &&
+		    isuop(t2->tok) &&
+		    t1->tok == T_VAL) {
+			/* unary operator */
+			t1->val = eval_uop(t2->tok, t1->val);
+			t1->place = t2->place;
+			token_destroy(t2);
+			tokenarray_remove(&tokens, num-2);
+			continue;
+		}
+		if (num >= 2 &&
+		    (num == 2 || isop(t3->tok) || t3->tok == T_RPAREN) &&
+		    t2->tok != T_LPAREN && t2->tok != T_VAL &&
+		    t1->tok == T_VAL) {
+			complain(&t2->place, "Invalid unary operator");
+			complain_fail();
+			token_destroy(t2);
+			tokenarray_remove(&tokens, num-2);
+			continue;
+		}
+
+			
+		t4 = (num >= 4) ? tokenarray_get(&tokens, num-4) : NULL;
+
+		if (num >= 4 &&
+		    t4->tok == T_VAL &&
+		    isbop(t3->tok) &&
+		    t2->tok == T_VAL &&
+		    (isbop(t1->tok) || !isop(t1->tok))) {
+			/* binary operator */
+			if (looser(t1->tok, t3->tok)) {
+				t4->val = eval_bop(&t3->place,
+						   t4->val, t3->tok, t2->val);
+				token_destroy(t2);
+				token_destroy(t3);
+				tokenarray_remove(&tokens, num-2);
+				tokenarray_remove(&tokens, num-3);
+				continue;
+			}
+			break;
+		}
+
+		t5 = (num >= 5) ? tokenarray_get(&tokens, num-5) : NULL;
+		t6 = (num >= 6) ? tokenarray_get(&tokens, num-6) : NULL;
+
+		if (num >=6 &&
+		    t6->tok == T_VAL &&
+		    t5->tok == T_QUES &&
+		    t4->tok == T_VAL &&
+		    t3->tok == T_COLON &&
+		    t2->tok == T_VAL &&
+		    !isop(t1->tok)) {
+			/* conditional expression */
+			t6->val = t6->val ? t4->val : t2->val;
+			token_destroy(t2);
+			token_destroy(t3);
+			token_destroy(t4);
+			token_destroy(t5);
+			tokenarray_remove(&tokens, num-2);
+			tokenarray_remove(&tokens, num-3);
+			tokenarray_remove(&tokens, num-4);
+			tokenarray_remove(&tokens, num-5);
+			continue;
+		}
+
+		if (num >= 2 &&
+		    t2->tok == T_LPAREN &&
+		    t1->tok == T_RPAREN) {
+			complain(&t1->place, "Value expected within ()");
+			complain_fail();
+			t1->tok = T_VAL;
+			t1->val = 0;
+			token_destroy(t1);
+			tokenarray_remove(&tokens, num-1);
+			continue;
+		}
+
+		if (num >= 2 &&
+		    t2->tok == T_VAL &&
+		    t1->tok == T_VAL) {
+			complain(&t1->place, "Operator expected");
+			complain_fail();
+			token_destroy(t1);
+			tokenarray_remove(&tokens, num-1);
+			continue;
+		}
+
+		if (num >= 2 &&
+		    isop(t2->tok) &&
+		    t1->tok == T_EOF) {
+			complain(&t1->place, "Value expected after operator");
+			complain_fail();
+			token_destroy(t2);
+			tokenarray_remove(&tokens, num-2);
+			continue;
+		}
+
+		if (num == 2 &&
+		    t2->tok == T_VAL &&
+		    t1->tok == T_RPAREN) {
+			complain(&t1->place, "Excess right parenthesis");
+			complain_fail();
+			token_destroy(t1);
+			tokenarray_remove(&tokens, num-1);
+			continue;
+		}
+
+		if (num == 3 &&
+		    t3->tok == T_LPAREN &&
+		    t2->tok == T_VAL &&
+		    t1->tok == T_EOF) {
+			complain(&t1->place, "Unclosed left parenthesis");
+			complain_fail();
+			token_destroy(t3);
+			tokenarray_remove(&tokens, num-3);
+			continue;
+		}
+
+		if (num == 2 &&
+		    t2->tok == T_VAL &&
+		    t1->tok == T_EOF) {
+			/* accepting state */
+			break;
+		}
+
+		if (num >= 1 &&
+		    t1->tok == T_EOF) {
+			/* any other configuration at eof is an error */
+			complain(&t1->place, "Parse error");
+			complain_fail();
+			break;
+		}
+
+		/* otherwise, wait for more input */
+		break;
+	}
+}
+
+static
+void
+token(struct place *p, enum tokens tok, int val)
+{
+	struct token *t;
+
+	t = token_create(p, tok, val);
+
+	tokenarray_add(&tokens, t, NULL);
+	tryreduce();
+}
+
+static
+int
+wordval(struct place *p, char *word)
+{
+	unsigned long val;
+	char *t;
+
+	if (word[0] >= '0' && word[0] <= '9') {
+		errno = 0;
+		val = strtoul(word, &t, 0);
+		if (errno || *t != '\0') {
+			complain(p, "Invalid integer constant");
+			complain_fail();
+			return 0;
+		}
+		if (val > INT_MAX) {
+			complain(p, "Integer constant too large");
+			complain_fail();
+			return INT_MAX;
+		}
+		return val;
+	}
+
+	/* if it's a symbol, warn and substitute 0. */
+	if (warns.undef) {
+		complain(p, "Warning: value of undefined symbol %s is 0",
+			 word);
+		if (mode.werror) {
+			complain_fail();
+		}
+	}
+	return 0;
+}
+
+static
+bool
+check_word(struct place *p, char *expr, size_t pos, size_t *len_ret)
+{
+	size_t len;
+	int val;
+	char tmp;
+
+	if (!strchr(alnum, expr[pos])) {
+		return false;
+	}
+	len = strspn(expr + pos, alnum);
+	tmp = expr[pos + len];
+	expr[pos + len] = '\0';
+	val = wordval(p, expr + pos);
+	expr[pos + len] = tmp;
+	token(p, T_VAL, val);
+	*len_ret = len;
+	return true;
+}
+
+static
+bool
+check_tokens_2(struct place *p, char *expr, size_t pos)
+{
+	unsigned i;
+
+	for (i=0; i<num_tokens_2; i++) {
+		if (expr[pos] == tokens_2[i].c1 &&
+		    expr[pos+1] == tokens_2[i].c2) {
+			token(p, tokens_2[i].tok, 0);
+			return true;
+		}
+	}
+	return false;
+}
+
+static
+bool
+check_tokens_1(struct place *p, char *expr, size_t pos)
+{
+	unsigned i;
+
+	for (i=0; i<num_tokens_1; i++) {
+		if (expr[pos] == tokens_1[i].c1) {
+			token(p, tokens_1[i].tok, 0);
+			return true;
+		}
+	}
+	return false;
+}
+
+static
+void
+tokenize(struct place *p, char *expr)
+{
+	size_t pos, len;
+
+	pos = 0;
+	while (expr[pos] != '\0') {
+		len = strspn(expr+pos, ws);
+		pos += len;
+		p->column += len;
+		if (check_word(p, expr, pos, &len)) {
+			pos += len;
+			p->column += len;
+			continue;
+		}
+		if (check_tokens_2(p, expr, pos)) {
+			pos += 2;
+			p->column += 2;
+			continue;
+		}
+		if (check_tokens_1(p, expr, pos)) {
+			pos++;
+			p->column++;
+			continue;
+		}
+		complain(p, "Invalid character %u in #if-expression",
+			 (unsigned char)expr[pos]);
+		complain_fail();
+		pos++;
+		p->column++;
+	}
+	token(p, T_EOF, 0);
+}
+
+bool
+eval(struct place *p, char *expr)
+{
+	struct token *t1, *t2;
+	unsigned num;
+	bool result;
+
+	tokenarray_init(&tokens);
+	tokenize(p, expr);
+
+	result = false;
+	num = tokenarray_num(&tokens);
+	if (num == 2) {
+		t1 = tokenarray_get(&tokens, num-1);
+		t2 = tokenarray_get(&tokens, num-2);
+		if (t1->tok == T_VAL &&
+		    t2->tok == T_EOF) {
+			result = t1->val != 0;
+		}
+	}
+
+	tokenarray_destroyall(&tokens);
+	tokenarray_cleanup(&tokens);
+	return result;
+}