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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,101 @@ | ||
| #define _CRT_SECURE_NO_WARNINGS | ||
| /* 功能摘要 | ||
| * 尝试执行赋值语句，在读到一条命令并去除其中可能存在的if/while等关键词后，首先执行的就是本文件中内容 | ||
| * 功能说明 | ||
| * 返回值反映了该语句是否为变量的赋值语句，返回值为0，则是，为-1，则不是 | ||
| * 功能逻辑 | ||
| * 在进行赋值时，会维护一个hash表，将变量名称以及它们的值作为键值对放在hash表中 | ||
| * 根据返回值 | ||
| */ | ||
| #include <stdio.h> | ||
| #include <ctype.h> | ||
| #include "varlib.h" | ||
| #include <Windows.h> | ||
|
|
||
| // 将$abc这样形式的字符串转变为$abc的值 | ||
| int eval(char* src, char* dest, int len) { | ||
| int pos; // dest指针 | ||
| char ch; // 当前字符 | ||
| char* varval; // 指向变量 | ||
|
|
||
| pos = 0; | ||
| while (ch = *src++) { | ||
| if (pos == len) // 越界检查 | ||
| return -1; | ||
| if (ch == '\0' || ch == EOF) { | ||
| break; | ||
| } | ||
| // 本来觉得需要，后来发现在splitline.c里面已经做过转义了，这里的$一定是变量开头的，\$一定是转义 | ||
| if (ch == '\\') | ||
| if (*src == '$') // 将\进行转义 | ||
| { | ||
| dest[pos++] = *src; | ||
| src++; | ||
| continue; | ||
| } | ||
|
|
||
| if (ch != '$') // 不为变量字符 | ||
| { | ||
| dest[pos++] = ch; // 写入缓冲区 | ||
| continue; | ||
| } | ||
|
|
||
| /* 是$的情况 */ | ||
| varval = getvar(&src); // 尝试读取变量名 | ||
| if (strlen(varval) + pos >= len) // 越界检查 | ||
| return -1; | ||
|
|
||
| strcpy(dest + pos, varval); // 写入变量 | ||
| pos += strlen(varval); // 移动指针 | ||
| } | ||
| dest[pos] = '\0'; | ||
| return pos; | ||
| } | ||
|
|
||
| char* getvar(char** srcp) { | ||
| /* | ||
| * 尝试读取变量的全称，在过程中检查合法性 | ||
| * 变量名称合法，返回变量名称 | ||
| * 否则返回$，并保持*srcp不动 | ||
| */ | ||
| char varname[VARLEN + 1]; // 变量名称 | ||
| int pos; // 写入缓冲区的指针位置 | ||
| char* cp; // 用来生成变量的指针 | ||
|
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||
| cp = *srcp; | ||
| pos = 0; | ||
|
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||
| while (is_an_idchar(*cp, pos)) // 当前字符合法 | ||
| varname[pos++] = *cp++; | ||
| varname[pos] = '\0'; | ||
| *srcp = cp; | ||
|
|
||
| if (pos > 0) { // 变量字符合法 | ||
| // cp = EVget(varname); | ||
| cp = value_lookup(varname); | ||
| //if (cp == NULL) // 本身找不到时返回值就是"" | ||
| // cp = (char*)""; | ||
| } | ||
| else | ||
| cp = (char*)"$"; /* else return the $ */ | ||
| return cp; | ||
| } | ||
|
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||
|
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| int isaname(char* s) { | ||
| /* | ||
| * 判定当前字符串是否是合法变量名 | ||
| */ | ||
| int pos = 0; | ||
| while (*s && is_an_idchar(*s, pos++)) | ||
| s++; | ||
|
|
||
| return ((!*s) && (pos != 0)); | ||
| } | ||
|
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||
| int is_an_idchar(char ch, int pos) { | ||
| /* | ||
| * 判定当前字符是否可以位于合法变量名中 | ||
| */ | ||
| return (isalpha(ch) || ch == '_' || (isdigit(ch) && pos > 0)); | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,9 @@ | ||
| a=2 | ||
| if echo $a | ||
| then | ||
| while [$a -lt 8] | ||
| do | ||
| a=$a+1 | ||
| echo a=$a | ||
| done | ||
| fi |
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