{"id":290,"date":"2009-11-20T23:10:24","date_gmt":"2009-11-20T15:10:24","guid":{"rendered":"http:\/\/115.29.108.60\/?p=290"},"modified":"2011-09-26T21:45:55","modified_gmt":"2011-09-26T13:45:55","slug":"lex","status":"publish","type":"post","link":"http:\/\/115.29.108.60\/?p=290","title":{"rendered":"Lex"},"content":{"rendered":"

\/\/ Lex.cpp : Defines the entry point for the console application.
\n\/\/<\/p>\n

#include “stdafx.h”
\n#include <stdio.h>
\n#include <string.h>
\n#include <ctype.h>
\n#include <process.h><\/p>\n

\/\/P83 3.4.2\u4fdd\u7559\u5b57\u548c\u6807\u8bc6\u7b26\u7684\u8bc6\u522b
\n\/\/\u521d\u59cb\u5316\u65f6\u5c31\u5c06\u5404\u4e2a\u4fdd\u7559\u5b57\u586b\u5165\u7b26\u53f7\u8868\u4e2d
\nconst char* KEYWORD[6] = {“begin”, “if”, “then”, “while”, “do”, “end”};
\nchar buffer[1024] = {0};\/\/\u8f93\u5165\u7f13\u51b2\u533a
\nchar token[10] = {0};\/\/\u8bcd\u7d20\uff0c\u6570\u7ec4\u5927\u5c0f\u9650\u5236\u7740\u6807\u8bc6\u7b26\u7684\u957f\u5ea6\u3002
\nint forward = 0, syn = -1;\/\/\u6e38\u6807\u548c\u79cd\u522b\u7801<\/p>\n

void analyzer();<\/p>\n

int main(int argc, char* argv[])
\n{
\n\u00a0\/\/\u8f93\u5165\uff0c\u4ee5#\u7ed3\u675f\u3002
\n\u00a0printf(“\u8bf7\u8f93\u5165\uff1a\uff08\u793a\u4f8b\u8f93\u5165begin x:=9;if x>0 then x:=2*x+1\/3;end#\uff09\\n”);
\n\u00a0char input;
\n\u00a0do
\n\u00a0{
\n\u00a0\u00a0input = getchar();
\n\u00a0\u00a0buffer[forward++] = input;
\n\u00a0}
\n\u00a0while(input != ‘#’);<\/p>\n

\u00a0\/\/\u5206\u6790\uff0c\u4ee5#\u7684\u79cd\u522b\u78010\u7ed3\u675f\u3002
\n\u00a0forward = 0;
\n\u00a0do
\n\u00a0{
\n\u00a0\u00a0analyzer();
\n\u00a0\u00a0printf(“(%d, %s)\\n”, syn, token);
\n\u00a0}
\n\u00a0while(syn != 0);
\n\u00a0system(“pause”);
\n\u00a0return 0;
\n}<\/p>\n

void analyzer()
\n{
\n\u00a0memset(token, ‘\\0’, sizeof(token));\/\/\u6e05\u7a7a\u524d\u4e00\u4e2a\u5df2\u5206\u6790\u7684\u8bcd\u7d20
\n\u00a0char ch = buffer[forward++];\/\/\u5f53\u524d\u5206\u6790\u7684\u5b57\u7b26
\n\u00a0while(isspace(ch))\/\/\u5ffd\u7565\u7a7a\u683c
\n\u00a0\u00a0ch = buffer[forward++];
\n\u00a0switch(ch)
\n\u00a0{
\n\u00a0\u00a0case ‘+’:
\n\u00a0\u00a0\u00a0token[0] = ch;
\n\u00a0\u00a0\u00a0syn = 13;
\n\u00a0\u00a0\u00a0return;
\n\u00a0\u00a0case ‘-‘:
\n\u00a0\u00a0\u00a0token[0] = ch;
\n\u00a0\u00a0\u00a0syn = 14;
\n\u00a0\u00a0\u00a0return;
\n\u00a0\u00a0case ‘*’:
\n\u00a0\u00a0\u00a0token[0] = ch;
\n\u00a0\u00a0\u00a0syn = 15;
\n\u00a0\u00a0\u00a0return;
\n\u00a0\u00a0case ‘\/’:
\n\u00a0\u00a0\u00a0token[0] = ch;
\n\u00a0\u00a0\u00a0syn = 16;
\n\u00a0\u00a0\u00a0return;
\n\u00a0\u00a0case ‘:’:
\n\u00a0\u00a0\u00a0token[0] = ch;
\n\u00a0\u00a0\u00a0if(buffer[forward] == ‘=’)
\n\u00a0\u00a0\u00a0{
\n\u00a0\u00a0\u00a0\u00a0forward++;
\n\u00a0\u00a0\u00a0\u00a0token[1] = ‘=’;
\n\u00a0\u00a0\u00a0\u00a0syn = 18;
\n\u00a0\u00a0\u00a0}
\n\u00a0\u00a0\u00a0else
\n\u00a0\u00a0\u00a0\u00a0syn = 17;
\n\u00a0\u00a0\u00a0return;
\n\u00a0\u00a0case ‘<‘:
\n\u00a0\u00a0\u00a0token[0] = ch;
\n\u00a0\u00a0\u00a0if(buffer[forward] == ‘>’)
\n\u00a0\u00a0\u00a0{
\n\u00a0\u00a0\u00a0\u00a0forward++;
\n\u00a0\u00a0\u00a0\u00a0token[1] = ‘>’;
\n\u00a0\u00a0\u00a0\u00a0syn = 21;
\n\u00a0\u00a0\u00a0}
\n\u00a0\u00a0\u00a0else if(buffer[forward] == ‘=’)
\n\u00a0\u00a0\u00a0{
\n\u00a0\u00a0\u00a0\u00a0forward++;
\n\u00a0\u00a0\u00a0\u00a0token[1] = ‘=’;
\n\u00a0\u00a0\u00a0\u00a0syn = 22;
\n\u00a0\u00a0\u00a0}
\n\u00a0\u00a0\u00a0else
\n\u00a0\u00a0\u00a0\u00a0syn = 20;
\n\u00a0\u00a0\u00a0return;
\n\u00a0\u00a0case ‘>’:
\n\u00a0\u00a0\u00a0token[0] = ch;
\n\u00a0\u00a0\u00a0if(buffer[forward] == ‘=’)
\n\u00a0\u00a0\u00a0{
\n\u00a0\u00a0\u00a0\u00a0forward++;
\n\u00a0\u00a0\u00a0\u00a0token[1] = ‘=’;
\n\u00a0\u00a0\u00a0\u00a0syn = 24;
\n\u00a0\u00a0\u00a0}
\n\u00a0\u00a0\u00a0else
\n\u00a0\u00a0\u00a0\u00a0syn = 23;
\n\u00a0\u00a0\u00a0return;
\n\u00a0\u00a0case ‘=’:
\n\u00a0\u00a0\u00a0token[0] = ch;
\n\u00a0\u00a0\u00a0syn = 25;
\n\u00a0\u00a0\u00a0return;
\n\u00a0\u00a0case ‘;’:
\n\u00a0\u00a0\u00a0token[0] = ch;
\n\u00a0\u00a0\u00a0syn = 26;
\n\u00a0\u00a0\u00a0return;
\n\u00a0\u00a0case ‘(‘:
\n\u00a0\u00a0\u00a0token[0] = ch;
\n\u00a0\u00a0\u00a0syn = 27;
\n\u00a0\u00a0\u00a0return;
\n\u00a0\u00a0case ‘)’:
\n\u00a0\u00a0\u00a0token[0] = ch;
\n\u00a0\u00a0\u00a0syn = 28;
\n\u00a0\u00a0\u00a0return;
\n\u00a0\u00a0case ‘#’:
\n\u00a0\u00a0\u00a0token[0] = ch;
\n\u00a0\u00a0\u00a0syn = 0;
\n\u00a0\u00a0\u00a0return;
\n\u00a0\u00a0default:
\n\u00a0\u00a0\u00a0int i = 0;
\n\u00a0\u00a0\u00a0if(isdigit(ch))\/\/\u6570\u5b57
\n\u00a0\u00a0\u00a0{
\n\u00a0\u00a0\u00a0\u00a0while(isdigit(ch))
\n\u00a0\u00a0\u00a0\u00a0{
\n\u00a0\u00a0\u00a0\u00a0\u00a0token[i] = ch;
\n\u00a0\u00a0\u00a0\u00a0\u00a0ch = buffer[forward++];
\n\u00a0\u00a0\u00a0\u00a0\u00a0i++;
\n\u00a0\u00a0\u00a0\u00a0}
\n\u00a0\u00a0\u00a0\u00a0forward–;
\n\u00a0\u00a0\u00a0\u00a0syn = 11;
\n\u00a0\u00a0\u00a0\u00a0return;
\n\u00a0\u00a0\u00a0}
\n\u00a0\u00a0\u00a0else if(isalpha(ch))\/\/\u5b57\u7b26\u7ec4\u6210\u4fdd\u7559\u5b57\u6216\u6807\u8bc6\u7b26
\n\u00a0\u00a0\u00a0{
\n\u00a0\u00a0\u00a0\u00a0while(isalnum(ch))
\n\u00a0\u00a0\u00a0\u00a0{
\n\u00a0\u00a0\u00a0\u00a0\u00a0token[i] = ch;
\n\u00a0\u00a0\u00a0\u00a0\u00a0ch = buffer[forward++];
\n\u00a0\u00a0\u00a0\u00a0\u00a0i++;
\n\u00a0\u00a0\u00a0\u00a0}
\n\u00a0\u00a0\u00a0\u00a0forward–;
\n\u00a0\u00a0\u00a0\u00a0for(int j = 0; j < 6; j++)
\n\u00a0\u00a0\u00a0\u00a0{
\n\u00a0\u00a0\u00a0\u00a0\u00a0if(strcmp(token, KEYWORD[j]) == 0)
\n\u00a0\u00a0\u00a0\u00a0\u00a0{
\n\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0syn = j + 1;
\n\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0return;
\n\u00a0\u00a0\u00a0\u00a0\u00a0}
\n\u00a0\u00a0\u00a0\u00a0}
\n\u00a0\u00a0\u00a0\u00a0syn = 10;
\n\u00a0\u00a0\u00a0\u00a0return;
\n\u00a0\u00a0\u00a0}
\n\u00a0}
\n}<\/p>\n","protected":false},"excerpt":{"rendered":"

\/\/ Lex.cpp : Defines the entry point for the console ap […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[25,20],"tags":[],"class_list":["post-290","post","type-post","status-publish","format-standard","hentry","category-tools","category-cplusplus"],"_links":{"self":[{"href":"http:\/\/115.29.108.60\/index.php?rest_route=\/wp\/v2\/posts\/290","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/115.29.108.60\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/115.29.108.60\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/115.29.108.60\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/115.29.108.60\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=290"}],"version-history":[{"count":3,"href":"http:\/\/115.29.108.60\/index.php?rest_route=\/wp\/v2\/posts\/290\/revisions"}],"predecessor-version":[{"id":888,"href":"http:\/\/115.29.108.60\/index.php?rest_route=\/wp\/v2\/posts\/290\/revisions\/888"}],"wp:attachment":[{"href":"http:\/\/115.29.108.60\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=290"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/115.29.108.60\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=290"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/115.29.108.60\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=290"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}