#include <stdio.h> #include <stdlib.h> #include <stdbool.h> #include <string.h> #include <assert.h> typedef struct Expression Expression; typedef struct TerminalExpression TerminalExpression; typedef struct AndExpression AndExpression; typedef struct Context Context; // 抽象表达式结构体 struct Expression { bool (*interpret)(struct Expression *, const char *); }; // 终结符表达式结构体 struct TerminalExpression { struct Expression base; char **infos; size_t num_infos; }; // 非终结符表达式结构体 struct AndExpression { struct Expression base; struct Expression *smartCity; struct Expression *smartPerson; }; // 上下文结构体 struct Context { struct Expression *smartAndExpr; }; bool and_interpret(struct Expression *self, const char *info); bool terminal_interpret(struct Expression *self, const char *info); // 创建终结符表达式 struct TerminalExpression *create_terminal_expression(char **datas, size_t num_datas) { struct TerminalExpression *expr = malloc(sizeof(struct TerminalExpression)); expr->base.interpret = terminal_interpret; expr->infos = malloc(num_datas * sizeof(char *)); expr->num_infos = num_datas; size_t i; for (i = 0; i < num_datas; i++) { expr->infos[i] = strdup(datas[i]); } return expr; } // 创建非终结符表达式 struct AndExpression *create_and_expression(struct Expression *city, struct Expression *person) { struct AndExpression *expr = malloc(sizeof(struct AndExpression)); expr->base.interpret = and_interpret; expr->smartCity = city; expr->smartPerson = person; return expr; } // 终结符表达式的解释操作 bool terminal_interpret(struct Expression *self, const char *info) { struct TerminalExpression *expr = (struct TerminalExpression *)self; size_t i; for (i = 0; i < expr->num_infos; i++) { if (strcmp(info, expr->infos[i]) == 0) { return true; } } return false; } // 非终结符表达式的解释操作 bool and_interpret(struct Expression *self, const char *info) { struct AndExpression *expr = (struct AndExpression *)self; char *buffer = strdup(info); char *token = strtok((char *)buffer, "的"); bool cityMatched = false; bool personMatched = false; while (token != NULL) { if (!cityMatched && expr->smartCity->interpret(expr->smartCity, token)) { cityMatched = true; } else if (!personMatched && expr->smartPerson->interpret(expr->smartPerson, token)) { personMatched = true; } else { if (buffer) free(buffer); return false; } token = strtok(NULL, "的"); } if (buffer) free(buffer); return cityMatched && personMatched; } // 创建上下文 struct Context *create_context() { struct Context *ctx = malloc(sizeof(struct Context)); char *citys[] = {"成都", "临沂"}; char *persons[] = {"老人", "儿童"}; struct TerminalExpression *cityExpr = create_terminal_expression(citys, sizeof(citys) / sizeof(citys[0])); struct TerminalExpression *personExpr = create_terminal_expression(persons, sizeof(persons) / sizeof(persons[0])); struct AndExpression *andExpr = create_and_expression(&cityExpr->base, &personExpr->base); ctx->smartAndExpr = &andExpr->base; return ctx; } // 上下文的解释操作 void context_is_free(struct Context *ctx, const char *info) { if (ctx->smartAndExpr->interpret(ctx->smartAndExpr, info)) { printf("%s , 您本次乘车免费\n", info); } else { printf("%s , 您本次乘车扣费2￥\n", info); } } // 销毁终结符表达式 void destroy_terminal_expression(struct TerminalExpression *expr) { size_t i; for (i = 0; i < expr->num_infos; i++) { free(expr->infos[i]); } free(expr->infos); free(expr); } // 销毁非终结符表达式 void destroy_and_expression(struct AndExpression *expr) { destroy_terminal_expression((struct TerminalExpression *)expr->smartCity); destroy_terminal_expression((struct TerminalExpression *)expr->smartPerson); free(expr); } // 销毁上下文 void destroy_context(struct Context *ctx) { struct AndExpression *andExpr = (struct AndExpression *)ctx->smartAndExpr; destroy_and_expression(andExpr); free(ctx); } int main() { struct Context *bus = create_context(); char *passengers[] = {"成都的老人", "成都的年轻人", "成都的儿童", "临沂的老人", "临沂的年轻人", "临沂的儿童"}; size_t i; for (i = 0; i < sizeof(passengers) / sizeof(passengers[0]); i++) { context_is_free(bus, passengers[i]); } destroy_context(bus); return 0; }