implement non-default plural rules for ngettext translations

the new code in dcngettext was written by me, and the expression
evaluator by Szabolcs Nagy (nsz).

diff --git a/src/locale/dcngettext.c b/src/locale/dcngettext.c
index 4f9e417..51e6522 100644 (file)
--- a/src/locale/dcngettext.c
+++ b/src/locale/dcngettext.c
@@ -4,6 +4,7 @@
 #include <errno.h>
 #include <limits.h>
 #include <sys/stat.h>
+#include <ctype.h>
 #include "locale_impl.h"
 #include "libc.h"
 #include "atomic.h"
@@ -95,6 +96,8 @@ struct msgcat {
        struct msgcat *next;
        const void *map;
        size_t map_size;
+       void *plural_rule;
+       int nplurals;
        char name[];
 };
 
@@ -107,6 +110,7 @@ weak_alias(dummy_gettextdomain, __gettextdomain);
 
 const unsigned char *__map_file(const char *, size_t *);
 int __munmap(void *, size_t);
+unsigned long __pleval(const char *, unsigned long);
 
 char *dcngettext(const char *domainname, const char *msgid1, const char *msgid2, unsigned long int n, int category)
 {
@@ -190,19 +194,53 @@ notrans:
        const char *trans = __mo_lookup(p->map, p->map_size, msgid1);
        if (!trans) goto notrans;
 
-       /* FIXME: support alternate plural rules */
-       if (n != 1) {
-               size_t l = strlen(trans);
-               if (l+1 >= p->map_size - (trans - (char *)p->map))
-                       goto notrans;
-               trans += l+1;
+       /* Non-plural-processing gettext forms pass a null pointer as
+        * msgid2 to request that dcngettext suppress plural processing. */
+       if (!msgid2) return (char *)trans;
+
+       if (!p->plural_rule) {
+               const char *rule = "n!=1;";
+               unsigned long np = 2;
+               const char *r = __mo_lookup(p->map, p->map_size, "");
+               char *z;
+               while (r && strncmp(r, "Plural-Forms:", 13)) {
+                       z = strchr(r, '\n');
+                       r = z ? z+1 : 0;
+               }
+               if (r) {
+                       r += 13;
+                       while (isspace(*r)) r++;
+                       if (!strncmp(r, "nplurals=", 9)) {
+                               np = strtoul(r+9, &z, 10);
+                               r = z;
+                       }
+                       while (*r && *r != ';') r++;
+                       if (*r) {
+                               r++;
+                               while (isspace(*r)) r++;
+                               if (!strncmp(r, "plural=", 7))
+                                       rule = r+7;
+                       }
+               }
+               a_store(&p->nplurals, np);
+               a_cas_p(&p->plural_rule, 0, (void *)rule);
+       }
+       if (p->nplurals) {
+               unsigned long plural = __pleval(p->plural_rule, n);
+               if (plural > p->nplurals) goto notrans;
+               while (plural--) {
+                       size_t l = strlen(trans);
+                       if (l+1 >= p->map_size - (trans - (char *)p->map))
+                               goto notrans;
+                       trans += l+1;
+               }
        }
        return (char *)trans;
 }
 
 char *dcgettext(const char *domainname, const char *msgid, int category)
 {
-       return dcngettext(domainname, msgid, msgid, 1, category);
+       return dcngettext(domainname, msgid, 0, 1, category);
 }
 
 char *dngettext(const char *domainname, const char *msgid1, const char *msgid2, unsigned long int n)
@@ -212,5 +250,5 @@ char *dngettext(const char *domainname, const char *msgid1, const char *msgid2,
 
 char *dgettext(const char *domainname, const char *msgid)
 {
-       return dcngettext(domainname, msgid, msgid, 1, LC_MESSAGES);
+       return dcngettext(domainname, msgid, 0, 1, LC_MESSAGES);
 }

diff --git a/src/locale/pleval.c b/src/locale/pleval.c
new file mode 100644 (file)
index 0000000..47aefc3
--- /dev/null
+++ b/src/locale/pleval.c
@@ -0,0 +1,197 @@
+#include <stdlib.h>
+#include <ctype.h>
+
+/*
+grammar:
+
+Start = Expr ';'
+Expr  = Or | Or '?' Expr ':' Expr
+Or    = And | Or '||' And
+And   = Eq | And '&&' Eq
+Eq    = Rel | Eq '==' Rel | Eq '!=' Rel
+Rel   = Add | Rel '<=' Add | Rel '>=' Add | Rel '<' Add | Rel '>' Add
+Add   = Mul | Add '+' Mul | Add '-' Mul
+Mul   = Term | Mul '*' Term | Mul '/' Term | Mul '%' Term
+Term  = '(' Expr ')' | '!' Term | decimal | 'n'
+
+internals:
+
+recursive descent expression evaluator with stack depth limit.
+eval* functions return the value of the subexpression and set
+the current string pointer to the next non-space char.
+*/
+
+struct st {
+       const char *s;
+       unsigned long n;
+       int err;
+};
+
+static const char *skipspace(const char *s)
+{
+       while (isspace(*s)) s++;
+       return s;
+}
+
+static unsigned long evalconst(struct st *st)
+{
+       char *e;
+       unsigned long n;
+       n = strtoul(st->s, &e, 10);
+       if (!isdigit(*st->s) || e == st->s || n == -1)
+               st->err = 1;
+       st->s = skipspace(e);
+       return n;
+}
+
+static unsigned long evalexpr(struct st *st, int d);
+
+static unsigned long evalterm(struct st *st, int d)
+{
+       unsigned long a;
+       if (d <= 0) {
+               st->err = 1;
+               return 0;
+       }
+       st->s = skipspace(st->s);
+       if (*st->s == '!') {
+               st->s++;
+               return !evalterm(st, d-1);
+       }
+       if (*st->s == '(') {
+               st->s++;
+               a = evalexpr(st, d-1);
+               if (*st->s != ')') {
+                       st->err = 1;
+                       return 0;
+               }
+               st->s = skipspace(st->s + 1);
+               return a;
+       }
+       if (*st->s == 'n') {
+               st->s = skipspace(st->s + 1);
+               return st->n;
+       }
+       return evalconst(st);
+}
+
+static unsigned long evalmul(struct st *st, int d)
+{
+       unsigned long b, a = evalterm(st, d-1);
+       int op;
+       for (;;) {
+               op = *st->s;
+               if (op != '*' && op != '/' && op != '%')
+                       return a;
+               st->s++;
+               b = evalterm(st, d-1);
+               if (op == '*') {
+                       a *= b;
+               } else if (!b) {
+                       st->err = 1;
+                       return 0;
+               } else if (op == '%') {
+                       a %= b;
+               } else {
+                       a /= b;
+               }
+       }
+}
+
+static unsigned long evaladd(struct st *st, int d)
+{
+       unsigned long a = 0;
+       int add = 1;
+       for (;;) {
+               a += (add?1:-1) * evalmul(st, d-1);
+               if (*st->s != '+' && *st->s != '-')
+                       return a;
+               add = *st->s == '+';
+               st->s++;
+       }
+}
+
+static unsigned long evalrel(struct st *st, int d)
+{
+       unsigned long b, a = evaladd(st, d-1);
+       int less, eq;
+       for (;;) {
+               if (*st->s != '<' && *st->s != '>')
+                       return a;
+               less = st->s[0] == '<';
+               eq = st->s[1] == '=';
+               st->s += 1 + eq;
+               b = evaladd(st, d-1);
+               a = (less ? a < b : a > b) || (eq && a == b);
+       }
+}
+
+static unsigned long evaleq(struct st *st, int d)
+{
+       unsigned long a = evalrel(st, d-1);
+       int neg;
+       for (;;) {
+               if ((st->s[0] != '=' && st->s[0] != '!') || st->s[1] != '=')
+                       return a;
+               neg = st->s[0] == '!';
+               st->s += 2;
+               a = evalrel(st, d-1) == a;
+               a ^= neg;
+       }
+}
+
+static unsigned long evaland(struct st *st, int d)
+{
+       unsigned long a = evaleq(st, d-1);
+       for (;;) {
+               if (st->s[0] != '&' || st->s[1] != '&')
+                       return a;
+               st->s += 2;
+               a = evaleq(st, d-1) && a;
+       }
+}
+
+static unsigned long evalor(struct st *st, int d)
+{
+       unsigned long a = evaland(st, d-1);
+       for (;;) {
+               if (st->s[0] != '|' || st->s[1] != '|')
+                       return a;
+               st->s += 2;
+               a = evaland(st, d-1) || a;
+       }
+}
+
+static unsigned long evalexpr(struct st *st, int d)
+{
+       unsigned long a1, a2, a3;
+       if (d <= 0) {
+               st->err = 1;
+               return 0;
+       }
+       a1 = evalor(st, d-1);
+       if (*st->s != '?')
+               return a1;
+       st->s++;
+       a2 = evalexpr(st, d-1);
+       if (*st->s != ':') {
+               st->err = 1;
+               return 0;
+       }
+       st->s++;
+       a3 = evalexpr(st, d-1);
+       return a1 ? a2 : a3;
+}
+
+unsigned long __pleval(const char *s, unsigned long n)
+{
+       unsigned long a;
+       struct st st;
+       st.s = s;
+       st.n = n;
+       st.err = 0;
+       a = evalexpr(&st, 100);
+       if (st.err || *st.s != ';')
+               return -1;
+       return a;
+}