bc2.c

来自「自己做的常用库和实现的数据结构。public domain.」· C语言 代码 · 共 168 行

#include "my.h"
#define MAX_LEN 80
#define sub_node_test(X)	if(X->tag == PTR) { \
					X->type.oprand = process_glist_link(X->type.new_head); \
					X->tag = RAND; \
					goto loop; \
				}
typedef enum { RAND, CODE, PTR } elem_type_tag;
typedef	union {
		double oprand;
		char opcode;
		struct glist_node *new_head;
} type_union;

typedef struct glist_node {
	elem_type_tag tag;
	type_union type;
	struct glist_node *next;
} GLIST;

void free_glist_next_node(GLIST *p)
{
	GLIST *t = p->next;
	p->next = t->next;
	free(t);
}
void free_whole_glist(GLIST *p)
{
	GLIST *t;
	while(p) {
		t = p->next;
		free(p);
		p = t;
	}
}
void process_unit(GLIST *t1, GLIST *t2, GLIST *t3)
{
	switch(t2->type.opcode) {
		case '+':
			t1->type.oprand += t3->type.oprand;
			break;
		case '-':
			t1->type.oprand -= t3->type.oprand;
			break;
		case '*':
			t1->type.oprand *= t3->type.oprand;
			break;
		case '/':
			t1->type.oprand /= t3->type.oprand;
			break;
		case '%':
			t1->type.oprand = (int)t1->type.oprand % (int)t3->type.oprand;
	}
	free_glist_next_node(t1);
	free_glist_next_node(t2);
}
double process_glist_link(GLIST *head)
{
	GLIST *p, *t1, *t2;
	double t;
loop:
	p=head;
	sub_node_test(p);
	if((t1 = p->next) == NULL) {
		t = p->type.oprand;
		free(p);
		return t;
	}
	t1=t1->next; sub_node_test(t1->type.new_head);
	if((t2=t1->next) == NULL) 
		process_unit(p, p->next, t1);
	else {
		t1=p->next;
		if( (t1->type.opcode == '+' || t1->type.opcode == '-') &&
		    (t2->type.opcode == '*' || t2->type.opcode == '/' || t2->type.opcode == '%')) {
			sub_node_test(t2->next->type.new_head);
			process_unit(t1->next, t2, t2->next);

		} else 
			process_unit(p, t1, t1->next);
	}
}
void parse_input(const char *input_buf, const char *input_buf_tail, char *tmp_buf, GLIST **glp)
{
	const char *p = input_buf, *head_tag, *tail_tag;
	size_t cnt, cnt2;
	for(;;) {
		if(*p == '(') {
			for(cnt=0,cnt2=0,tail_tag = head_tag = p; p != input_buf_tail; p++) {
				if(*p == '(')
					cnt++;
				else if(*p == ')' && ++cnt2 == cnt) {
					tail_tag = p;
					break;
				}
			}
			if(head_tag == tail_tag)
				goto input_format_error;
			*glp = (GLIST *)mem('m', sizeof(GLIST));
			(*glp)->tag = PTR;
			parse_input(head_tag+1, tail_tag-1, tmp_buf, &((*glp)->type.new_head));
			if(p++ == input_buf_tail) 
				goto over;
		} else if( *p == '-' || *p == '+' ) {
			if(p == input_buf_tail) 
				goto input_format_error;
			if(isdigit( *(p+1)) || *(p+1) == '(' || *(p+1) == '.') {
				*glp = (GLIST *)mem('m', sizeof(GLIST));
				(*glp)->tag = RAND;
				(*glp)->type.oprand = 0.0;
			}
		} else if(isdigit(*p) || *p == '.') {
			for(head_tag = tail_tag = p; p != input_buf_tail; p++) 
				if(! isdigit(*p) && *p != '.') {
					tail_tag = --p;
					break;
				}
			yastrcpy(tmp_buf, head_tag, tail_tag);
			*glp = (GLIST *)mem('m', sizeof(GLIST));
			(*glp)->tag = RAND;
			(*glp)->type.oprand = atof(tmp_buf);
			if(p++ == input_buf_tail) 
				goto over;
		}
		if(p == input_buf_tail) 
			goto input_format_error;
		*glp = (GLIST *)mem('m', sizeof(GLIST));
		(*glp)->tag = CODE;
		(*glp)->type.opcode = *p++;
		parse_input(p, input_buf_tail, tmp_buf, &((*glp)->next));
	}
input_format_error:
	free_whole_glist(*glp);
	fatal_error("Fatal: input format error");
over:
	(*glp)->next = NULL;
	return;
}

void preprocess_input(char *input_buf, size_t nmemb, char **input_buf_tail)
{
	int c;
	size_t left=0, right=0, i=0;
	while( (c=getchar()) != '\n' && c != EOF && i < nmemb-1) 
		if(isdigit(c) || c=='+' || c=='-' || c=='*' || c=='/' || c=='%' || c=='(' || c== ')' || c=='.') {
			input_buf[i++] = c;
			if(c=='(')
				left++;
			else if(c==')')
				right++;
		}
	if(left != right)
		fatal_error("Fatal: input format error");
	*input_buf_tail = &input_buf[i-1];
}
int main(void)
{
	char input_buf[MAX_LEN+1], tmp_buf[MAX_LEN+1];
	char *input_buf_tail;
	double result;
	GLIST bc_glist, *glp = &bc_glist;
	preprocess_input(input_buf, MAX_LEN+1, &input_buf_tail);	
	parse_input(input_buf, input_buf_tail, tmp_buf, &glp);
	result = process_glist_link(glp);
	printf("%f\n", result);
	return EXIT_SUCCESS;
}