#pragma prototyped

static const char usage[] =

"the result to standard output. The character \b0\b will be written "

"to indicate a zero value and nothing will be written to indicate an "

"empty string.]"

"way by the shell, \bsh\b(1), and \bexpr\b is provided primarily "

"for backward compatibility.]"

"one that can not be identified as an integer. Integer-valued "

"arguments may be preceded by a unary plus or minus sign. Because "

"many of the operators use characters that have special meaning to "

"the shell, they must be quoted when entered from the shell.]"

"of increasing precedence within groups. All of the operators are "

"left associative. The symbols \aexpr1\a and \aexpr2\a represent "

"expressions formed from strings and integers and the following "

"operators:]{"

"[+\aexpr1\a \b|\b \aexpr2\a?Returns the evaluation of \aexpr1\a if "

"it is neither null nor 0, otherwise returns the evaluation of expr2.]"

"[+\aexpr1\a \b&\b \aexpr2\a?Returns the evaluation of \aexpr1\a if "

"neither expression evaluates to null or 0, otherwise returns 0.]"

"[+\aexpr1\a \aop\a \aexpr2\a?Returns the result of a decimal integer "

"comparison if both arguments are integers; otherwise, returns the "

"result of a string comparison using the locale-specific collation "

"sequence. The result of each comparison will be 1 if the specified "

"relationship is true, or 0 if the relationship is false. \aop\a "

"can be one of the following:]{"

"[+=?Equal.]"

"[+==?Equal.]"

"[+>?Greater than.]"

"[+>=?Greater than or equal to.]"

"[+<?Less than.]"

"[+<=?Less than or equal to.]"

"[+!=?Not equal to.]"

"}"

"[+\aexpr1\a \aop\a \aexpr2\a?Where \aop\a is \b+\b or \b-\b; "

"addition or subtraction of decimal integer-valued arguments.]"

"[+\aexpr1\a \aop\a \aexpr2\a?Where \aop\a is \b*\b, \b/\b or \b%\b; "

"multiplication, division, or remainder of the decimal "

"integer-valued arguments.]"

"[+\aexpr1\a \b::\b \aexpr2\a?The matching operator : compares "

"\aexpr1\a with \aexpr2\a, which must be a BRE. Normally, "

"the matching operator returns the number of bytes matched "

"and 0 on failure. However, if the pattern contains at "

"least one sub-expression [\\( . . .\\)]], the string "

"corresponding to \\1 will be returned.]"

"[+( \aexpr1\a )?Grouping symbols. An expression can "

"be placed within parenthesis to change precedence.]"

"[+match\b \astring\a \aexpr\a?Equivalent to \astring\a \b:\b "

"\aexpr\a.]"

"[+substr\b \astring\a \apos\a \alength\a?\alength\a character "

"substring of \astring\a starting at \apos\a "

"(counting from 1).]"

"[+index\b \astring\a \achars\a?The position in \astring\a "

"(counting from 1) of the leftmost occurrence of any "

"character in \achars\a.]"

"[+length\b \astring\a?The number of characters in \astring\a.]"

"[+quote\b \atoken\a?Treat \atoken\a as a string operand.]"

"}"

"a \b-\b will be treated as operands. Portable applications "

"should use \b--\b to indicate end of options.]"

"[+0?The expression is neither null nor 0.]"

"[+1?The expression is null or 0.]"

"[+2?Invalid expressions.]"

"[+>2?An error occurred.]"

"}"

;

#include <cmd.h>

#include <regex.h>

#define T_ADD 0x100

#define T_MULT 0x200

#define T_CMP 0x400

#define T_FUN 0x800

#define T_OP 7

#define T_NUM 1

#define T_STR 2

#define OP_EQ (T_CMP|0)

#define OP_GT (T_CMP|1)

#define OP_LT (T_CMP|2)

#define OP_GE (T_CMP|3)

#define OP_LE (T_CMP|4)

#define OP_NE (T_CMP|5)

#define OP_PLUS (T_ADD|0)

#define OP_MINUS (T_ADD|1)

#define OP_MULT (T_MULT|0)

#define OP_DIV (T_MULT|1)

#define OP_MOD (T_MULT|2)

#define OP_INDEX (T_FUN|0)

#define OP_LENGTH (T_FUN|1)

#define OP_MATCH (T_FUN|2)

#define OP_QUOTE (T_FUN|3)

#define OP_SUBSTR (T_FUN|4)

#define numeric(np) ((np)->type&T_NUM)

static const struct Optable_s

{

const char opname[3];

int op;

}

optable[] =

{

"|", '|',

"&", '&',

"=", OP_EQ,

"==", OP_EQ,

">", OP_GT,

"<", OP_LT,

">=", OP_GE,

"<=", OP_LE,

"!=", OP_NE,

"+", OP_PLUS,

"-", OP_MINUS,

"*", OP_MULT,

"/", OP_DIV,

"%", OP_MOD,

":", ':',

"(", '(',

")", ')'

};

typedef struct Node_s

{

int type;

long num;

char *str;

} Node_t;

typedef struct State_s

{

int standard;

char** arglist;

char buf[36];

} State_t;

static int expr_or(State_t*, Node_t*);

static int getnode(State_t* state, Node_t *np)

{

register char* sp;

register char* cp;

register int i;

register int j;

register int k;

register int tok;

char* ep;

if (!(cp = *state->arglist++))

error(ERROR_exit(2), "argument expected");

if (!state->standard)

switch (cp[0])

{

case 'i':

if (cp[1] == 'n' && !strcmp(cp, "index"))

{

if (!(cp = *state->arglist++))

error(ERROR_exit(2), "string argument expected");

if (!(ep = *state->arglist++))

error(ERROR_exit(2), "chars argument expected");

np->num = (ep = strpbrk(cp, ep)) ? (ep - cp + 1) : 0;

np->type = T_NUM;

goto next;

}

break;

case 'l':

if (cp[1] == 'e' && !strcmp(cp, "length"))

{

if (!(cp = *state->arglist++))

error(ERROR_exit(2), "string argument expected");

np->num = strlen(cp);

np->type = T_NUM;

goto next;

}

break;

case 'm':

if (cp[1] == 'a' && !strcmp(cp, "match"))

{

if (!(np->str = *state->arglist++))

error(ERROR_exit(2), "pattern argument expected");

np->type = T_STR;

return ':';

}

break;

case 'q':

if (cp[1] == 'u' && !strcmp(cp, "quote") && !(cp = *state->arglist++))

error(ERROR_exit(2), "string argument expected");

break;

case 's':

if (cp[1] == 'u' && !strcmp(cp, "substr"))

{

if (!(sp = *state->arglist++))

error(ERROR_exit(2), "string argument expected");

if (!(cp = *state->arglist++))

error(ERROR_exit(2), "position argument expected");

i = strtol(cp, &ep, 10);

if (*ep || --i < 0)

i = -1;

if (!(cp = *state->arglist++))

error(ERROR_exit(2), "length argument expected");

j = strtol(cp, &ep, 10);

if (*ep)

j = -1;

k = strlen(sp);

if (i < 0 || i >= k || j < 0)

sp = "";

else

{

sp += i;

k -= i;

if (j < k)

sp[j] = 0;

}

np->type = T_STR;

np->str = sp;

goto next;

}

break;

}

if (*cp=='(' && cp[1]==0)

{

tok = expr_or(state, np);

if (tok != ')')

error(ERROR_exit(2),"closing parenthesis missing");

}

else

{

np->type = T_STR;

np->str = cp;

if (*cp)

{

np->num = strtol(np->str,&ep,10);

if (!*ep)

np->type |= T_NUM;

}

}

next:

if (!(cp = *state->arglist))

return 0;

state->arglist++;

for (i=0; i < sizeof(optable)/sizeof(*optable); i++)

if (*cp==optable[i].opname[0] && cp[1]==optable[i].opname[1])

return optable[i].op;

error(ERROR_exit(2),"%s: unknown operator argument",cp);

return 0;

}

static int expr_cond(State_t* state, Node_t *np)

{

register int tok = getnode(state, np);

while (tok==':')

{

regex_t re;

regmatch_t match[2];

int n;

Node_t rp;

char *cp;

tok = getnode(state, &rp);

if (np->type&T_STR)

cp = np->str;

else

sfsprintf(cp=state->buf,sizeof(state->buf),"%d",np->num);

np->num = 0;

np->type = T_NUM;

if (n = regcomp(&re, rp.str, REG_LEFT|REG_LENIENT))

regfatal(&re, ERROR_exit(2), n);

if (!(n = regexec(&re, cp, elementsof(match), match, 0)))

{

if (re.re_nsub > 0)

{

np->type = T_STR;

if (match[1].rm_so >= 0)

{

np->str = cp + match[1].rm_so;

np->str[match[1].rm_eo - match[1].rm_so] = 0;

np->num = strtol(np->str,&cp,10);

if (cp!=np->str && *cp==0)

np->type |= T_NUM;

}

else

np->str = "";

}

else

np->num = match[0].rm_eo - match[0].rm_so;

}

else if (n != REG_NOMATCH)

regfatal(&re, ERROR_exit(2), n);

else if (re.re_nsub)

{

np->str = "";

np->type = T_STR;

}

regfree(&re);

}

return tok;

}

static int expr_mult(State_t* state, Node_t *np)

{

register int tok = expr_cond(state, np);

while ((tok&~T_OP)==T_MULT)

{

Node_t rp;

int op = (tok&T_OP);

tok = expr_cond(state, &rp);

if (!numeric(np) || !numeric(&rp))

error(ERROR_exit(2),"non-numeric argument");

if (op && rp.num==0)

error(ERROR_exit(2),"division by zero");

switch(op)

{

case 0:

np->num *= rp.num;

break;

case 1:

np->num /= rp.num;

break;

case 2:

np->num %= rp.num;

}

np->type = T_NUM;

}

return tok;

}

static int expr_add(State_t* state, Node_t *np)

{

register int tok = expr_mult(state, np);

while ((tok&~T_OP)==T_ADD)

{

Node_t rp;

int op = (tok&T_OP);

tok = expr_mult(state, &rp);

if (!numeric(np) || !numeric(&rp))

error(ERROR_exit(2),"non-numeric argument");

if (op)

np->num -= rp.num;

else

np->num += rp.num;

np->type = T_NUM;

}

return tok;

}

static int expr_cmp(State_t* state, Node_t *np)

{

register int tok = expr_add(state, np);

while ((tok&~T_OP)==T_CMP)

{

Node_t rp;

register char *left,*right;

char buff1[36],buff2[36];

int op = (tok&T_OP);

tok = expr_add(state, &rp);

if (numeric(&rp) && numeric(np))

op |= 010;

else

{

if (np->type&T_STR)

left = np->str;

else

sfsprintf(left=buff1,sizeof(buff1),"%d",np->num);

if (rp.type&T_STR)

right = rp.str;

else

sfsprintf(right=buff2,sizeof(buff2),"%d",rp.num);

}

switch(op)

{

case 0:

np->num = streq(left,right);

break;

case 1:

np->num = (strcoll(left,right)>0);

break;

case 2:

np->num = (strcoll(left,right)<0);

break;

case 3:

np->num = (strcoll(left,right)>=0);

break;

case 4:

np->num = (strcoll(left,right)<=0);

break;

case 5:

np->num = !streq(left,right);

break;

case 010:

np->num = (np->num==rp.num);

break;

case 011:

np->num = (np->num>rp.num);

break;

case 012:

np->num = (np->num<rp.num);

break;

case 013:

np->num = (np->num>=rp.num);

break;

case 014:

np->num = (np->num<=rp.num);

break;

case 015:

np->num = (np->num!=rp.num);

break;

}

np->type = T_NUM;

}

return tok;

}

static int expr_and(State_t* state, Node_t *np)

{

register int tok = expr_cmp(state, np);

while (tok=='&')

{

Node_t rp;

tok = expr_cmp(state, &rp);

if ((numeric(&rp) && rp.num==0) || *rp.str==0)

{

np->num = 0;

np->type=T_NUM;

}

}

return tok;

}

static int expr_or(State_t* state, Node_t *np)

{

register int tok = expr_and(state, np);

while (tok=='|')

{

Node_t rp;

tok = expr_and(state, &rp);

if ((numeric(np) && np->num==0) || *np->str==0)

*np = rp;

}

return tok;

}

b_expr(int argc, char** argv, Shbltin_t* context)

{

State_t state;

Node_t node;

int n;

cmdinit(argc, argv, context, ERROR_CATALOG, 0);

state.standard = !!conformance(0, 0);

#if 0

if (state.standard)

state.arglist = argv+1;

else

#endif

{

while (n=optget(argv, usage))

{

/*

if(n=='?')

error(ERROR_usage(2), "%s", opt_info.arg);

if (opt_info.option[1] != '?')

break;

error(ERROR_usage(2), "%s", opt_info.arg);

}

if (error_info.errors)

error(ERROR_usage(2),"%s",optusage((char*)0));

state.arglist = argv+opt_info.index;

}

if (expr_or(&state, &node))

error(ERROR_exit(2),"syntax error");

if (node.type&T_STR)

{

if (*node.str)

sfprintf(sfstdout,"%s\n",node.str);

}

else

sfprintf(sfstdout,"%d\n",node.num);

return numeric(&node)?node.num==0:*node.str==0;

}