Add fmt to mstring.

bbidulock · May 7, 2024 · 67df1d4 · 67df1d4
1 parent dfb6fec
commit 67df1d4
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Showing 3 changed files with 62 additions and 0 deletions.
diff --git a/src/mstring.cc b/src/mstring.cc
@@ -357,4 +357,56 @@ mstring mstring::match(const char* regex, const char* flags) const {
     return mstring(data() + pos.rm_so, size_t(pos.rm_eo - pos.rm_so));
 }
 
+#include <errno.h>
+#include <stdarg.h>
+
+void mstring::fmt(const char* fmt, ...) {
+    const int en = errno;
+    va_list ap;
+    va_start(ap, fmt);
+    size_t len = strlen(fmt);
+    for (const char* s = fmt; *s; ++s) {
+        if (*s == '%' && s[1]) {
+            s++;
+            if (*s == 's') {
+                len += strlen(va_arg(ap, const char *));
+            }
+            if (*s == 'm') {
+                len += strlen(strerror(en));
+            }
+        }
+    }
+    va_end(ap);
+    MStringRef ref(len);
+    va_start(ap, fmt);
+    int i = 0;
+    for (const char* s = fmt; *s; ++s) {
+        if (*s == '%' && s[1]) {
+            s++;
+            if (*s == 's') {
+                const char* arg = va_arg(ap, const char *);
+                for (int k = 0; arg[k]; ++k)
+                    ref[i++] = arg[k];
+            }
+            if (*s == 'm') {
+                const char* arg = strerror(en);
+                for (int k = 0; arg[k]; ++k)
+                    ref[i++] = arg[k];
+            }
+            if (*s == '%') {
+                ref[i++] = '%';
+            }
+        } else {
+            ref[i++] = *s;
+        }
+    }
+    ref[i] = '\0';
+    va_end(ap);
+    release();
+    fRef = ref;
+    fOffset = 0;
+    fCount = i;
+    acquire();
+}
+
 // vim: set sw=4 ts=4 et:
diff --git a/src/mstring.h b/src/mstring.h
@@ -139,6 +139,7 @@ class mstring {
 
     operator const char *() { return c_str(); }
     const char* c_str();
+    void fmt(const char* fmt, ...);
 };
 
 inline bool operator==(const char* s, const mstring& c) { return c == s; }

diff --git a/src/strtest.cc b/src/strtest.cc
@@ -9,6 +9,7 @@
 #include <unistd.h>
 #include <sys/types.h>
 #include <fnmatch.h>
+#include <errno.h>
 
 char const *ApplicationName = "strtest";
 static const char source[] = __FILE__;
@@ -256,6 +257,14 @@ static void test_mstring()
     expect(u, "#fffff");
     u = mstring("f#ffffff").match("#f{5}");
     expect(u, "#fffff");
+
+    u.fmt("abc %s ghi", "def");
+    expect(u, "abc def ghi");
+    u.fmt("%s %s %s", "abc", "def", "ghi");
+    expect(u, "abc def ghi");
+    errno = EFAULT;
+    u.fmt("%m");
+    expect(u, strerror(errno));
 }
 
 static void test_upath()