150 lines
2.5 KiB
C
150 lines
2.5 KiB
C
#include <stdio.h>
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#include <string.h>
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#include <ctype.h>
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#include <stdlib.h>
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#define MAXTOKENS 100
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#define MAXTOKENLEN 64
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enum type_tag { IDENTIFIED, QUALIFIER, TYPE };
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struct token {
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char type;
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char string[MAXTOKENLEN];
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};
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int top = -1;
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struct token stack[MAXTOKENS];
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struct token this;
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#define pop stack[top--]
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#define push(s) stack[++top] = s;
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enum type_tag classify_string(void)
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{
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char *s = this.string;
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if (!strcmp(s, "const"))
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{
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strcpy(s, "read-only");
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return QUALIFIER;
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}
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if (!strcmp(s, "volatile")) return QUALIFIER;
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if (!strcmp(s, "void")) return TYPE;
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if (!strcmp(s, "char")) return TYPE;
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if (!strcmp(s, "signed")) return TYPE;
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if (!strcmp(s, "unsigned")) return TYPE;
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if (!strcmp(s, "short")) return TYPE;
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if (!strcmp(s, "int")) return TYPE;
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if (!strcmp(s, "long")) return TYPE;
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if (!strcmp(s, "float")) return TYPE;
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if (!strcmp(s, "double")) return TYPE;
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if (!strcmp(s, "struct")) return TYPE;
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if (!strcmp(s, "union")) return TYPE;
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if (!strcmp(s, "enum")) return TYPE;
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return IDENTIFIED;
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}
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void gettoken(void)
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{
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char *p = this.string;
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/* 略过空白字符 */
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while ((*p = getchar()) == ' ');
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if (isalnum(*p))
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{
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/*读入的标识符以A-Z,0-9开头。 */
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while (isalnum( *++p = getchar() ));
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ungetc(*p, stdin);
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*p = '\0';
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this.type = classify_string();
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return;
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}
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if (*p == '*')
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{
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strcpy(this.string, "pointer to");
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this.type = '*';
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return;
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}
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this.string[1] = '\0';
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this.type = *p;
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return;
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}
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void read_to_first_identifer(void)
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{
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gettoken();
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while (this.type != IDENTIFIED)
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{
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push(this);
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gettoken();
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}
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printf("%s is \n", this.string);
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gettoken();
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return;
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}
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void deal_with_arrays(void)
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{
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while (this.type == '[')
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{
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printf("array ");
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gettoken();
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if (isdigit(this.string[0]))
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{
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printf("0..%d", atoi(this.string) - 1);
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gettoken();
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}
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gettoken();
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printf(" of ");
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}
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}
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void deal_with_function_args()
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{
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while(this.type != ')'){
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gettoken();
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}
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gettoken();
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printf("function returning ");
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}
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void deal_with_pointers()
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{
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while (stack[top].type == '*')
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{
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printf("%s ", pop.string);
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}
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}
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void deal__with_declarator()
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{
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switch (this.type)
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{
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case '[': deal_with_arrays(); break;
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case '(': deal_with_function_args();
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}
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deal_with_pointers();
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while (top >= 0)
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{
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if (stack[top].type == '(')
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{
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pop;
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gettoken();
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deal__with_declarator();
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}else {
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printf("%s ", pop.string);
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}
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}
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}
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int main()
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{
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/* 将标记压入堆栈中，直到遇到标识符 */
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read_to_first_identifer();
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deal__with_declarator();
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printf("\n");
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return 0;
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}
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