编译原理及实践编程练习原代码

#include "globals.h" #include "util.h" #include "scan.h" #include "parse.h" static TokenType token; static TreeNode *stmt_sequence(void); static TreeNode *statement(void); static TreeNode *if_stmt(void); static TreeNode *repeat_stmt(void); static TreeNode *assign_stmt(void); static TreeNode *read_stmt(void); static TreeNode *write_stmt(void); static TreeNode *arith_exp(void); static TreeNode *rel_exp_or(void); static TreeNode *rel_exp_and(void); static TreeNode *rel_exp_not(void); static TreeNode *bol_exp(void); static TreeNode *simple_exp(void); static TreeNode *term(void); static TreeNode *factor(void); static void syntaxError(char *message) { fprintf(listing, "\n>> "); fprintf(listing, "Syntax error at line %d: %s", lineno, message); Error = TRUE; } static void match(TokenType expected) { if (token == expected) token = getToken(); else { syntaxError("unexpected token -> "); printToken(token, tokenString); fprintf(listing, " "); } } TreeNode *stmt_sequence(void) { TreeNode *t = statement(); TreeNode *p = t; while(token == SEMI){ TreeNode *q; match(SEMI); q = statement(); if (q != NULL) { if (t == NULL) t = p = q; else { p->sibling = q; p = q; } } } return t; } TreeNode *statement(void) { TreeNode *t = NULL; switch (token) { case IF: t = if_stmt(); break; case REPEAT: t = repeat_stmt(); break; case ID: t = assign_stmt(); break; case READ: t = read_stmt(); break; case WRITE: t = write_stmt(); break; default: syntaxError("unexpected token -> "); printToken(token, tokenString); token = getToken(); break; } return t; } TreeNode *if_stmt(void) { TreeNode *t = newStmtNode(IfK); match(IF); if (t != NULL) t->child[0] = rel_exp_and(); match(THEN); if (t != NULL) t->child[1] = stmt_sequence(); if (token == ELSE) { match(ELSE); if (t != NULL) t->child[2] = stmt_sequence(); } match(END); return t; } TreeNode *repeat_stmt(void) { TreeNode *t = newStmtNode(RepeatK); match(REPEAT); if ( t!= NULL) t->child[0] = stmt_sequence(); match(UNTIL); if (t != NULL) t->child[1] = rel_exp_and(); return t; } TreeNode *assign_stmt(void) { TreeNode *t = newStmtNode(AssignK); if ((t != NULL) && (token == ID)) t->attr.name = copyString(tokenString); match(ID); match(ASSIGN); if (t != NULL) t->child[0] = arith_exp(); return t; } TreeNode *read_stmt(void) { TreeNode *t = newStmtNode(ReadK); match(READ); if ((t != NULL) && (token == ID)) t->attr.name = copyString(tokenString); match(ID); return t; } TreeNode *write_stmt(void) { TreeNode *t = newStmtNode(WriteK); match(WRITE); if (t != NULL) t->child[0] = arith_exp(); return t; } TreeNode *rel_exp_and(void) { TreeNode *t = rel_exp_or(); if(token == AND) { TreeNode *p = newExpNode(OpK); if (p != NULL) { p->child[0] = t; p->attr.op = token; t = p; } match(AND); if (t != NULL) t->child[1] = rel_exp_or(); } return t; } TreeNode *rel_exp_or(void) { TreeNode *t = rel_exp_not(); if(token == OR) { TreeNode *p = newExpNode(OpK); if (p != NULL){ p->child[0] = t; p->attr.op = token; t = p; } match(OR); if (t != NULL) t->child[1] = rel_exp_not(); } return t; } TreeNode *rel_exp_not(void) { TreeNode *t; if (token == LPAREN) { match(LPAREN); t = rel_exp_or(); match(LPAREN); } else if (token == NOT) { match(NOT); t = rel_exp_not(); } else t = bol_exp(); return t; } TreeNode *bol_exp(void) { TreeNode *t = arith_exp(); if ((token == LT) || (token == EQ)) { TreeNode *p = newExpNode(OpK); if (p != NULL) { p->child[0] = t; p->attr.op = token; t = p; } match(token); if (t != NULL) t->child[1] = arith_exp(); } return t; } TreeNode *arith_exp(void) { TreeNode *t = term(); while ((token == PLUS) || (token == MINUS)) { TreeNode *p = newExpNode(OpK); if (p != NULL) { p->child[0] = t; p->attr.op = token; t = p; match(token); t->child[1] = term(); } } return t; } TreeNode *term(void) { TreeNode *t = factor(); while ((token == TIMES) || (token == MINUS)) { TreeNode *p = newExpNode(OpK); if (p != NULL) { p->child[0] = t; p->attr.op = token; t = p; match(token); t->child[1] = factor(); } } return t; } TreeNode *factor(void) { TreeNode *t = NULL; switch(token) { case NUM: t = newExpNode(ConstK); if ((t != NULL) && (token == NUM)) t->attr.val = atoi(tokenString); match(NUM); break; case ID: t = newExpNode(IdK); if ((t != NULL) && (token == ID)) t->attr.name = copyString(tokenString); match(ID); break; case LPAREN: match(LPAREN); t = arith_exp(); match(RPAREN); break; default: syntaxError("unexpected token -> "); printToken(token, tokenString); token = getToken(); break; } return t; } TreeNode *parse(void) { TreeNode *t; token = getToken(); t = stmt_sequence(); if (token != ENDFILE) syntaxError("Code ends before file\n"); return t; }