psql: Case preserving completion of SQL key words

Instead of always completing SQL key words in upper case, look at the
word being completed and match the case.

reviewed by Fujii Masao

src/bin/psql/tab-complete.c

@@ -132,6 +132,7 @@ static const char *const * completion_charpp;	/* to pass a list of strings */
 static const char *completion_info_charp;		/* to pass a second string */
 static const char *completion_info_charp2;		/* to pass a third string */
 static const SchemaQuery *completion_squery;	/* to pass a SchemaQuery */
+static bool completion_case_sensitive;			/* completion is case sensitive */
 
 /*
  * A few macros to ease typing. You can use these to complete the given
@@ -155,15 +156,24 @@ do { \
 	matches = completion_matches(text, complete_from_schema_query); \
 } while (0)
 
+#define COMPLETE_WITH_LIST_CS(list) \
+do { \
+	completion_charpp = list; \
+	completion_case_sensitive = true; \
+	matches = completion_matches(text, complete_from_list); \
+} while (0)
+
 #define COMPLETE_WITH_LIST(list) \
 do { \
 	completion_charpp = list; \
+	completion_case_sensitive = false; \
 	matches = completion_matches(text, complete_from_list); \
 } while (0)
 
 #define COMPLETE_WITH_CONST(string) \
 do { \
 	completion_charp = string; \
+	completion_case_sensitive = false; \
 	matches = completion_matches(text, complete_from_const); \
 } while (0)
 
@@ -671,6 +681,7 @@ static char *complete_from_const(const char *text, int state);
 static char **complete_from_variables(char *text,
 						const char *prefix, const char *suffix);
 
+static char *pg_strdup_same_case(const char *s, const char *ref);
 static PGresult *exec_query(const char *query);
 
 static void get_previous_words(int point, char **previous_words, int nwords);
@@ -771,7 +782,7 @@ psql_completion(char *text, int start, int end)
 
 	/* If a backslash command was started, continue */
 	if (text[0] == '\\')
-		COMPLETE_WITH_LIST(backslash_commands);
+		COMPLETE_WITH_LIST_CS(backslash_commands);
 
 	/* Variable interpolation */
 	else if (text[0] == ':' && text[1] != ':')
@@ -2907,7 +2918,7 @@ psql_completion(char *text, int start, int end)
 			"null", "fieldsep", "tuples_only", "title", "tableattr",
 		"linestyle", "pager", "recordsep", NULL};
 
-		COMPLETE_WITH_LIST(my_list);
+		COMPLETE_WITH_LIST_CS(my_list);
 	}
 	else if (strcmp(prev2_wd, "\\pset") == 0)
 	{
@@ -2917,14 +2928,14 @@ psql_completion(char *text, int start, int end)
 			{"unaligned", "aligned", "wrapped", "html", "latex",
 			"troff-ms", NULL};
 
-			COMPLETE_WITH_LIST(my_list);
+			COMPLETE_WITH_LIST_CS(my_list);
 		}
 		else if (strcmp(prev_wd, "linestyle") == 0)
 		{
 			static const char *const my_list[] =
 			{"ascii", "old-ascii", "unicode", NULL};
 
-			COMPLETE_WITH_LIST(my_list);
+			COMPLETE_WITH_LIST_CS(my_list);
 		}
 	}
 	else if (strcmp(prev_wd, "\\set") == 0)
@@ -3030,7 +3041,7 @@ create_or_drop_command_generator(const char *text, int state, bits32 excluded)
 	{
 		if ((pg_strncasecmp(name, text, string_length) == 0) &&
 			!(words_after_create[list_index - 1].flags & excluded))
-			return pg_strdup(name);
+			return pg_strdup_same_case(name, text);
 	}
 	/* if nothing matches, return NULL */
 	return NULL;
@@ -3298,7 +3309,7 @@ complete_from_list(const char *text, int state)
 	{
 		list_index = 0;
 		string_length = strlen(text);
-		casesensitive = true;
+		casesensitive = completion_case_sensitive;
 		matches = 0;
 	}
 
@@ -3313,7 +3324,14 @@ complete_from_list(const char *text, int state)
 
 		/* Second pass is case insensitive, don't bother counting matches */
 		if (!casesensitive && pg_strncasecmp(text, item, string_length) == 0)
+		{
+			if (completion_case_sensitive)
 				return pg_strdup(item);
+			else
+				/* If case insensitive matching was requested initially, return
+				 * it in the case of what was already entered. */
+				return pg_strdup_same_case(item, text);
+		}
 	}
 
 	/*
@@ -3343,12 +3361,16 @@ complete_from_list(const char *text, int state)
 static char *
 complete_from_const(const char *text, int state)
 {
-	(void) text;				/* We don't care about what was entered
-								 * already. */
-
 	psql_assert(completion_charp);
 	if (state == 0)
+	{
+		if (completion_case_sensitive)
 			return pg_strdup(completion_charp);
+		else
+			/* If case insensitive matching was requested initially, return it
+			 * in the case of what was already entered. */
+			return pg_strdup_same_case(completion_charp, text);
+	}
 	else
 		return NULL;
 }
@@ -3394,7 +3416,7 @@ complete_from_variables(char *text, const char *prefix, const char *suffix)
 	}
 
 	varnames[nvars] = NULL;
-	COMPLETE_WITH_LIST((const char * const *) varnames);
+	COMPLETE_WITH_LIST_CS((const char * const *) varnames);
 
 	for (i = 0; i < nvars; i++)
 		free(varnames[i]);
@@ -3407,6 +3429,31 @@ complete_from_variables(char *text, const char *prefix, const char *suffix)
 /* HELPER FUNCTIONS */
 
 
+/*
+ * Make a pg_strdup copy of s and convert it to the same case as ref.
+ */
+static char *
+pg_strdup_same_case(const char *s, const char *ref)
+{
+	char *ret, *p;
+	unsigned char first = ref[0];
+
+	if (isalpha(first))
+	{
+		ret = pg_strdup(s);
+		if (islower(first))
+			for (p = ret; *p; p++)
+				*p = pg_tolower((unsigned char) *p);
+		else
+			for (p = ret; *p; p++)
+				*p = pg_toupper((unsigned char) *p);
+		return ret;
+	}
+	else
+		return pg_strdup(s);
+}
+
+
 /*
  * Execute a query and report any errors. This should be the preferred way of
  * talking to the database in this file.