Fleshed out upb_string further. Now upb_def's only

unresolved references are upb_src.

Makefile

@@ -87,7 +87,8 @@ tests/test.proto.pb: tests/test.proto
 	protoc tests/test.proto -otests/test.proto.pb
 
 TESTS=tests/test_string \
-    tests/test_table
+    tests/test_table \
+    tests/test_def
 tests: $(TESTS)
 
 OTHER_TESTS=tests/tests \

core/upb_def.c

@@ -44,13 +44,12 @@ static void upb_deflist_push(upb_deflist *l, upb_def *d) {
  *   join("", "Baz") -> "Baz"
  * Caller owns a ref on the returned string. */
 static upb_string *upb_join(upb_string *base, upb_string *name) {
-  upb_string *joined = upb_strdup(base);
+  if (upb_string_len(base) == 0) {
-  upb_strlen_t len = upb_string_len(joined);
+    return upb_string_getref(name);
-  if(len > 0) {
+  } else {
-    upb_string_getrwbuf(joined, len + 1)[len] = UPB_SYMBOL_SEPARATOR;
+    return upb_string_asprintf(UPB_STRFMT "." UPB_STRFMT,
+                               UPB_STRARG(base), UPB_STRARG(name));
   }
-  upb_strcat(joined, name);
-  return joined;
 }
 
 // Qualify the defname for all defs starting with offset "start" with "str".

core/upb_string.c

@@ -82,7 +82,7 @@ char *upb_string_getrwbuf(upb_string *str, upb_strlen_t len) {
   }
   str->len = len;
   str->ptr = str->cached_mem;
-  return str->ptr;
+  return str->cached_mem;
 }
 
 void upb_string_substr(upb_string *str, upb_string *target_str,
@@ -92,3 +92,31 @@ void upb_string_substr(upb_string *str, upb_string *target_str,
   str->ptr = upb_string_getrobuf(target_str) + start;
   str->len = len;
 }
+
+void upb_string_vprintf(upb_string *str, const char *format, va_list args) {
+  // Try once without reallocating.  We have to va_copy because we might have
+  // to call vsnprintf again.
+  uint32_t size = UPB_MAX(upb_string_size(str), 16);
+  char *buf = upb_string_getrwbuf(str, size);
+  va_list args_copy;
+  va_copy(args_copy, args);
+  uint32_t true_size = vsnprintf(buf, size, format, args_copy);
+  va_end(args_copy);
+
+  if (true_size > size) {
+    // Need to reallocate.
+    str = upb_string_tryrecycle(str);
+    buf = upb_string_getrwbuf(str, true_size);
+    vsnprintf(buf, true_size, format, args);
+  }
+  str->len = true_size;
+}
+
+upb_string *upb_string_asprintf(const char *format, ...) {
+  upb_string *str = upb_string_new();
+  va_list args;
+  va_start(args, format);
+  upb_string_vprintf(str, format, args);
+  va_end(args);
+  return str;
+}

core/upb_string.h

@@ -25,6 +25,7 @@
 
 #include <assert.h>
 #include <string.h>
+#include <stdarg.h>
 #include "upb_atomic.h"
 #include "upb.h"
 
@@ -37,7 +38,7 @@ extern "C" {
 struct _upb_string {
   // The pointer to our currently active data.  This may be memory we own
   // or a pointer into memory we don't own.
-  char *ptr;
+  const char *ptr;
 
   // If non-NULL, this is a block of memory we own.  We keep this cached even
   // if "ptr" is currently aliasing memory we don't own.
@@ -111,16 +112,25 @@ INLINE void upb_string_endread(upb_string *str) { (void)str; }
 //   }
 upb_string *upb_string_tryrecycle(upb_string *str);
 
-// The three options for setting the contents of a string.  These may only be
+// The options for setting the contents of a string.  These may only be called
-// called when a string is first created or recycled; once other functions have
+// when a string is first created or recycled; once other functions have been
-// been called on the string, these functions are not allowed until the string
+// called on the string, these functions are not allowed until the string is
-// is recycled.
+// recycled.
 
 // Gets a pointer suitable for writing to the string, which is guaranteed to
 // have at least "len" bytes of data available.  The size of the string will
 // become "len".
 char *upb_string_getrwbuf(upb_string *str, upb_strlen_t len);
 
+// Replaces the contents of str with the contents of the given printf.
+void upb_string_vprintf(upb_string *str, const char *format, va_list args);
+INLINE void upb_string_printf(upb_string *str, const char *format, ...) {
+  va_list args;
+  va_start(args, format);
+  upb_string_vprintf(str, format, args);
+  va_end(args);
+}
+
 // Sets the contents of "str" to be the given substring of "target_str", to
 // which the caller must own a ref.
 void upb_string_substr(upb_string *str, upb_string *target_str,
@@ -144,7 +154,7 @@ void upb_string_substr(upb_string *str, upb_string *target_str,
 /* upb_string library functions ***********************************************/
 
 // Named like their <string.h> counterparts, these are all safe against buffer
-// overflow.  These only use the public upb_string interface.
+// overflow.  For the most part these only use the public upb_string interface.
 
 // More efficient than upb_strcmp if all you need is to test equality.
 INLINE bool upb_streql(upb_string *s1, upb_string *s2) {
@@ -163,6 +173,17 @@ INLINE bool upb_streql(upb_string *s1, upb_string *s2) {
 // Like strcmp().
 int upb_strcmp(upb_string *s1, upb_string *s2);
 
+// Compare a upb_string with memory or a NULL-terminated C string.
+INLINE bool upb_streqllen(upb_string *str, const void *buf, upb_strlen_t len) {
+  return len == upb_string_len(str) &&
+      memcmp(upb_string_getrobuf(str), buf, len) == 0;
+}
+
+INLINE bool upb_streqlc(upb_string *str, const void *buf) {
+  // Could be made one-pass.
+  return upb_streqllen(str, buf, strlen((const char*)buf));
+}
+
 // Like upb_strcpy, but copies from a buffer and length.
 INLINE void upb_strcpylen(upb_string *dest, const void *src, upb_strlen_t len) {
   memcpy(upb_string_getrwbuf(dest, len), src, len);
@@ -175,10 +196,10 @@ INLINE void upb_strcpy(upb_string *dest, upb_string *src) {
 }
 
 // Like upb_strcpy, but copies from a NULL-terminated string.
-INLINE void upb_strcpyc(upb_string *dest, const char *src) {
+INLINE void upb_strcpyc(upb_string *dest, const void *src) {
   // This does two passes over src, but that is necessary unless we want to
   // repeatedly re-allocate dst, which seems worse.
-  upb_strcpylen(dest, src, strlen(src));
+  upb_strcpylen(dest, src, strlen((const char*)src));
 }
 
 // Returns a new string whose contents are a copy of s.
@@ -200,11 +221,18 @@ INLINE upb_string *upb_strdupc(const char *src) {
 void upb_strcat(upb_string *s, upb_string *append);
 
 // Returns a new string that is a substring of the given string.
-upb_string *upb_strslice(upb_string *s, int offset, int len);
+INLINE upb_string *upb_strslice(upb_string *s, int offset, int len) {
+  upb_string *str = upb_string_new();
+  upb_string_substr(str, s, offset, len);
+  return str;
+}
 
 // Reads an entire file into a newly-allocated string.
 upb_string *upb_strreadfile(const char *filename);
 
+// Returns a new string with the contents of the given printf.
+upb_string *upb_string_asprintf(const char *format, ...);
+
 #ifdef __cplusplus
 }  /* extern "C" */
 #endif

tests/test_string.c

@@ -17,7 +17,7 @@ int main() {
   assert(upb_string_len(str) == (sizeof(static_str) - 1));
   const char *robuf = upb_string_getrobuf(str);
   assert(robuf != NULL);
-  assert(memcmp(robuf, static_str, upb_string_len(str)) == 0);
+  assert(upb_streqlc(str, static_str));
   upb_string_endread(str);
 
   upb_string *str2 = upb_string_tryrecycle(str);
@@ -28,7 +28,7 @@ int main() {
   upb_strcpyc(str, "XX");
   const char *robuf2 = upb_string_getrobuf(str);
   assert(robuf2 == robuf);
-  assert(memcmp(robuf2, "XX", 2) == 0);
+  assert(upb_streqlc(str, "XX"));
 
   // Make string alias part of another string.
   str2 = upb_strdupc("WXYZ");
@@ -51,6 +51,19 @@ int main() {
   const char *robuf5 = upb_string_getrobuf(str);
   assert(robuf5 == robuf);
 
+  // Resetting str to something very long should require new data to be
+  // allocated.
+  str = upb_string_tryrecycle(str);
+  const char longstring[] = "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX";
+  upb_strcpyc(str, longstring);
+  const char *robuf6 = upb_string_getrobuf(str);
+  assert(robuf6 != robuf);
+  assert(upb_streqlc(str, longstring));
+
+  // Test printf.
+  str = upb_string_tryrecycle(str);
+  upb_string_printf(str, "Number: %d, String: %s", 5, "YO!");
+
   upb_string_unref(str);
   upb_string_unref(str2);
 }