From 15604083c7323a1bcd7a591a6025aca98bd57fd2 Mon Sep 17 00:00:00 2001 From: Joshua Haberman Date: Sat, 2 Jan 2010 22:08:25 -0800 Subject: Move string representations back upb.h -> upb_data.h. --- src/upb_data.h | 31 ++++++++++++++++++++++++++++++- 1 file changed, 30 insertions(+), 1 deletion(-) (limited to 'src/upb_data.h') diff --git a/src/upb_data.h b/src/upb_data.h index 9c55cee..88ca9af 100644 --- a/src/upb_data.h +++ b/src/upb_data.h @@ -165,6 +165,35 @@ INLINE bool _upb_data_unref(upb_data *d) { /* upb_string *****************************************************************/ +// We have several different representations for string, depending on whether +// it has a refcount (and likely in the future, depending on whether it is a +// slice of another string). We could just have one representation with +// members that are sometimes unused, but this is wasteful in memory. The +// flags that are always part of the first word tell us which representation +// to use. +// +// In a way, this is like inheritance but instead of using a virtual pointer, +// we do switch/case in every "virtual" method. This may sound expensive but +// in many cases the different cases compile to exactly the same code, so there +// is no branch. + +struct upb_norefcount_string { + uint32_t byte_size_and_flags; + upb_strlen_t byte_len; + // We expect the data to be 8-bit clean (uint8_t), but char* is such an + // ingrained convention that we follow it. + char *ptr; +}; + +// Used for a string with a refcount. +struct upb_refcounted_string { + upb_data base; + upb_strlen_t byte_len; + char *ptr; + uint32_t byte_size; +}; + + // Returns a newly constructed, refcounted string which starts out empty. // Caller owns one ref on it. The returned string will not be frozen. upb_strptr upb_string_new(void); @@ -296,7 +325,7 @@ upb_strptr upb_strreadfile(const char *filename); // // upb_strtr mystr_ptr = UPB_STRLIT("biscuits"); // -typedef upb_norefcount_string upb_static_string; +typedef struct upb_norefcount_string upb_static_string; #define UPB_STATIC_STRING_INIT_LEN(str, len) {0 | UPB_DATA_FROZEN, len, str} #define UPB_STATIC_STRING_INIT(str) UPB_STATIC_STRING_INIT_LEN(str, sizeof(str)-1) #define UPB_STATIC_STRING_PTR_INIT(static_string) {&static_string} -- cgit v1.2.3