impr: text - replace function

src/sqlite3-text.c

@@ -641,6 +641,88 @@ static void sqlite3_pad(sqlite3_context* context, int argc, sqlite3_value** argv
 
 #pragma endregion
 
+#pragma region Other modifications
+
+// Replaces all old substrings with new substrings in the original string.
+// text_replace(str, old, new)
+// [pg-compatible] replace(string, from, to)
+static void sqlite3_replace_all(sqlite3_context* context, int argc, sqlite3_value** argv) {
+    assert(argc == 3);
+
+    const char* src = (char*)sqlite3_value_text(argv[0]);
+    if (src == NULL) {
+        sqlite3_result_null(context);
+        return;
+    }
+
+    const char* old = (char*)sqlite3_value_text(argv[1]);
+    if (old == NULL) {
+        sqlite3_result_null(context);
+        return;
+    }
+
+    const char* new = (char*)sqlite3_value_text(argv[2]);
+    if (new == NULL) {
+        sqlite3_result_null(context);
+        return;
+    }
+
+    ByteString s_src = bstring.from_cstring(src, sqlite3_value_bytes(argv[0]));
+    ByteString s_old = bstring.from_cstring(old, sqlite3_value_bytes(argv[1]));
+    ByteString s_new = bstring.from_cstring(new, sqlite3_value_bytes(argv[2]));
+    ByteString s_res = bstring.replace_all(s_src, s_old, s_new);
+    const char* res = bstring.to_cstring(s_res);
+    sqlite3_result_text(context, res, -1, SQLITE_TRANSIENT);
+    bstring.free(s_src);
+    bstring.free(s_old);
+    bstring.free(s_new);
+    bstring.free(s_res);
+}
+
+// Replaces old substrings with new substrings in the original string,
+// but not more than `count` times.
+// text_replace(str, old, new, count)
+static void sqlite3_replace(sqlite3_context* context, int argc, sqlite3_value** argv) {
+    assert(argc == 4);
+
+    const char* src = (char*)sqlite3_value_text(argv[0]);
+    if (src == NULL) {
+        sqlite3_result_null(context);
+        return;
+    }
+
+    const char* old = (char*)sqlite3_value_text(argv[1]);
+    if (old == NULL) {
+        sqlite3_result_null(context);
+        return;
+    }
+
+    const char* new = (char*)sqlite3_value_text(argv[2]);
+    if (new == NULL) {
+        sqlite3_result_null(context);
+        return;
+    }
+
+    if (sqlite3_value_type(argv[3]) != SQLITE_INTEGER) {
+        sqlite3_result_error(context, "count parameter should be integer", -1);
+        return;
+    }
+    int count = sqlite3_value_int(argv[3]);
+    // treat negative count as zero
+    count = count < 0 ? 0 : count;
+
+    ByteString s_src = bstring.from_cstring(src, sqlite3_value_bytes(argv[0]));
+    ByteString s_old = bstring.from_cstring(old, sqlite3_value_bytes(argv[1]));
+    ByteString s_new = bstring.from_cstring(new, sqlite3_value_bytes(argv[2]));
+    ByteString s_res = bstring.replace(s_src, s_old, s_new, count);
+    const char* res = bstring.to_cstring(s_res);
+    sqlite3_result_text(context, res, -1, SQLITE_TRANSIENT);
+    bstring.free(s_src);
+    bstring.free(s_old);
+    bstring.free(s_new);
+    bstring.free(s_res);
+}
+
 // Reverses a string.
 // text_reverse(str)
 static void sqlite3_reverse(sqlite3_context* context, int argc, sqlite3_value** argv) {
@@ -661,6 +743,8 @@ static void sqlite3_reverse(sqlite3_context* context, int argc, sqlite3_value**
     rstring.free(s_res);
 }
 
+#pragma endregion
+
 // substring
 // utf8 text_slice(str, start [,end])
 // utf8 text_substring(str, start [,length])
@@ -745,6 +829,10 @@ __declspec(dllexport)
     sqlite3_create_function(db, "text_rpad", -1, flags, rstring.pad_right, sqlite3_pad, 0, 0);
     sqlite3_create_function(db, "rpad", -1, flags, rstring.pad_right, sqlite3_pad, 0, 0);
 
+    // other modifications
+    sqlite3_create_function(db, "text_replace", 3, flags, 0, sqlite3_replace_all, 0, 0);
+    sqlite3_create_function(db, "replace", 3, flags, 0, sqlite3_replace_all, 0, 0);
+    sqlite3_create_function(db, "text_replace", 4, flags, 0, sqlite3_replace, 0, 0);
     sqlite3_create_function(db, "text_reverse", 1, flags, 0, sqlite3_reverse, 0, 0);
     sqlite3_create_function(db, "reverse", 1, flags, 0, sqlite3_reverse, 0, 0);
     return SQLITE_OK;

src/text/bstring.c

@@ -363,7 +363,7 @@ static ByteString string_repeat(ByteString str, size_t count) {
 
 // string_replace replaces the `old` substring with the `new` substring in the original string,
 // but not more than `max_count` times.
-static ByteString string_replace(ByteString str, ByteString old, ByteString new, size_t max_count) {
+static ByteString string_replace(ByteString str, ByteString old, ByteString new, int max_count) {
     // count matches of the old string in the source string
     size_t count = string_count(str, old);
     if (count == 0) {

src/text/bstring.h

@@ -45,7 +45,7 @@ struct bstring_ns {
     ByteString (*concat)(ByteString* strings, size_t count);
     ByteString (*repeat)(ByteString str, size_t count);
 
-    ByteString (*replace)(ByteString str, ByteString old, ByteString new, size_t max_count);
+    ByteString (*replace)(ByteString str, ByteString old, ByteString new, int max_count);
     ByteString (*replace_all)(ByteString str, ByteString old, ByteString new);
     ByteString (*reverse)(ByteString str);
 

test/text.sql

@@ -363,6 +363,41 @@ select '17_14', text_rpad('hello', 8, '*') = 'hello***';
 select '17_15', text_rpad('hello', 8, 'xo') = 'helloxox';
 select '17_16', text_rpad('мир', 6, 'хо') = 'мирхох';
 
+-- Replace all
+select '18_01', text_replace(null, 'a', '*') is null;
+select '18_02', text_replace('abc', null, '*') is null;
+select '18_03', text_replace('abc', 'a', null) is null;
+select '18_04', text_replace('hello', 'l', '*')  = 'he**o';
+select '18_05', text_replace('hello', 'l', 'xo')  = 'hexoxoo';
+select '18_06', text_replace('hello', 'ell', '*')  = 'h*o';
+select '18_07', text_replace('hello', 'ello', 'argh')  = 'hargh';
+select '18_08', text_replace('hello', 'hello', '-')  = '-';
+select '18_09', text_replace('hello', '', '*')  = 'hello';
+select '18_10', text_replace('hello', 'l', '')  = 'heo';
+select '18_11', text_replace('', 'l', '*')  = '';
+select '18_12', text_replace('нетто', 'т', 'три')  = 'нетритрио';
+
+-- Replace
+select '19_01', text_replace(null, 'a', '*', 1) is null;
+select '19_02', text_replace('abc', null, '*', 1) is null;
+select '19_03', text_replace('abc', 'a', null, 1) is null;
+select '19_04', text_replace('hello', 'l', '*', 2)  = 'he**o';
+select '19_05', text_replace('hello', 'l', 'xo', 2)  = 'hexoxoo';
+select '19_06', text_replace('hello', 'ell', '*', 1)  = 'h*o';
+select '19_07', text_replace('hello', 'ello', 'argh', 1)  = 'hargh';
+select '19_08', text_replace('hello', 'hello', '-', 1)  = '-';
+select '19_09', text_replace('hello', '', '*', 1)  = 'hello';
+select '19_10', text_replace('hello', 'l', '', 2)  = 'heo';
+select '19_11', text_replace('', 'l', '*', 1)  = '';
+select '19_12', text_replace('нетто', 'т', 'три', 2)  = 'нетритрио';
+
+select '19_21', text_replace('hello', 'l', '*', -1)  = 'hello';
+select '19_22', text_replace('hello', 'l', '*', 0)  = 'hello';
+select '19_23', text_replace('hello', 'l', '*', 1)  = 'he*lo';
+select '19_24', text_replace('hello', 'l', '*', 2)  = 'he**o';
+select '19_25', text_replace('hello', 'l', '*', 3)  = 'he**o';
+select '19_16', text_replace('нетто', 'т', 'три', 1)  = 'нетрито';
+
 -- Reverse string
 select 'x_01', text_reverse(null) is NULL;
 select 'x_02', text_reverse('hello') = 'olleh';

test/text/bstring.test.c

@@ -566,6 +566,26 @@ static void test_replace(void) {
         bstring.free(res);
     }
 
+    {
+        ByteString old = bstring.from_cstring("o", 1);
+        ByteString new = bstring.from_cstring("***", 3);
+        ByteString res = bstring.replace(str, old, new, 1);
+        assert(eq(res, "hell*** world"));
+        bstring.free(old);
+        bstring.free(new);
+        bstring.free(res);
+    }
+
+    {
+        ByteString old = bstring.from_cstring("o", 1);
+        ByteString new = bstring.from_cstring("***", 3);
+        ByteString res = bstring.replace(str, old, new, 2);
+        assert(eq(res, "hell*** w***rld"));
+        bstring.free(old);
+        bstring.free(new);
+        bstring.free(res);
+    }
+
     {
         ByteString old = bstring.from_cstring("e", 1);
         ByteString new = bstring.from_cstring("***", 3);