Add multi-character TRIM function (#8015)

* Add multi-character TRIM function

* Follow Adriano's suggestion

Co-authored-by: Adriano dos Santos Fernandes <529415+asfernandes@users.noreply.github.com>

---------

Co-authored-by: Dmitry Yemanov <dyemanov@users.noreply.github.com>
Co-authored-by: Adriano dos Santos Fernandes <529415+asfernandes@users.noreply.github.com>

doc/sql.extensions/README.trim

@@ -18,11 +18,16 @@ Format:
 	<trim character> ::=
 		<value expression>
 
+	<multi-character trim function> ::=
+		{ BTRIM | LTRIM | RTRIM } <left paren> <value expression> [ <comma> <trim character> ] <right paren>
+
 Syntax Rules:
 	1) If <trim specification> is not specified, BOTH is assumed.
 	2) If <trim character> is not specified, ' ' is assumed.
 	3) If <trim specification> and/or <trim character> is specified, FROM should be specified.
 	4) If <trim specification> and <trim character> is not specified, FROM should not be specified.
+	5) multi-character trim function accepts a sequence of characters as the second argument and will remove all
+		leading, trailing, or both occurrences of any of these characters, regardless of their ordering.
 
 Examples:
 A)
@@ -36,3 +41,8 @@ B)
 		trim(rdb$relation_name) || ' is a system table'
 		from rdb$relations
 		where rdb$system_flag = 1;
+
+C)
+	select
+		ltrim('baobab is a tree', 'aboe')
+		from rdb$database;

src/common/ParserTokens.h

@@ -507,6 +507,9 @@ PARSER_TOKEN(TOK_TRANSACTION, "TRANSACTION", true)
 PARSER_TOKEN(TOK_TRAPS, "TRAPS", true)
 PARSER_TOKEN(TOK_TRIGGER, "TRIGGER", false)
 PARSER_TOKEN(TOK_TRIM, "TRIM", false)
+PARSER_TOKEN(TOK_BTRIM, "BTRIM", false)
+PARSER_TOKEN(TOK_LTRIM, "LTRIM", false)
+PARSER_TOKEN(TOK_RTRIM, "RTRIM", false)
 PARSER_TOKEN(TOK_TRUE, "TRUE", false)
 PARSER_TOKEN(TOK_TRUNC, "TRUNC", true)
 PARSER_TOKEN(TOK_TRUSTED, "TRUSTED", true)

src/dsql/ExprNodes.cpp

@@ -12531,9 +12531,10 @@ ValueExprNode* SysFuncCallNode::dsqlPass(DsqlCompilerScratch* dsqlScratch)
 
 static RegisterNode<TrimNode> regTrimNode({blr_trim});
 
-TrimNode::TrimNode(MemoryPool& pool, UCHAR aWhere, ValueExprNode* aValue, ValueExprNode* aTrimChars)
+TrimNode::TrimNode(MemoryPool& pool, UCHAR aWhere, UCHAR aWhat, ValueExprNode* aValue, ValueExprNode* aTrimChars)
 	: TypedNode<ValueExprNode, ExprNode::TYPE_TRIM>(pool),
 	  where(aWhere),
+	  what(aWhat),
 	  value(aValue),
 	  trimChars(aTrimChars)
 {
@@ -12544,9 +12545,9 @@ DmlNode* TrimNode::parse(thread_db* tdbb, MemoryPool& pool, CompilerScratch* csb
 	UCHAR where = csb->csb_blr_reader.getByte();
 	UCHAR what = csb->csb_blr_reader.getByte();
 
-	TrimNode* node = FB_NEW_POOL(pool) TrimNode(pool, where);
+	TrimNode* node = FB_NEW_POOL(pool) TrimNode(pool, where, what);
 
-	if (what == blr_trim_characters)
+	if (what == blr_trim_characters || what == blr_trim_multi_characters)
 		node->trimChars = PAR_parse_value(tdbb, csb);
 
 	node->value = PAR_parse_value(tdbb, csb);
@@ -12567,7 +12568,7 @@ string TrimNode::internalPrint(NodePrinter& printer) const
 
 ValueExprNode* TrimNode::dsqlPass(DsqlCompilerScratch* dsqlScratch)
 {
-	TrimNode* node = FB_NEW_POOL(dsqlScratch->getPool()) TrimNode(dsqlScratch->getPool(), where,
+	TrimNode* node = FB_NEW_POOL(dsqlScratch->getPool()) TrimNode(dsqlScratch->getPool(), where, what,
 		doDsqlPass(dsqlScratch, value), doDsqlPass(dsqlScratch, trimChars));
 
 	// Try to force trimChars to be same type as value: TRIM(? FROM FIELD)
@@ -12595,7 +12596,7 @@ void TrimNode::genBlr(DsqlCompilerScratch* dsqlScratch)
 
 	if (trimChars)
 	{
-		dsqlScratch->appendUChar(blr_trim_characters);
+		dsqlScratch->appendUChar(what);
 		GEN_expr(dsqlScratch, trimChars);
 	}
 	else
@@ -12665,7 +12666,7 @@ void TrimNode::getDesc(thread_db* tdbb, CompilerScratch* csb, dsc* desc)
 
 ValueExprNode* TrimNode::copy(thread_db* tdbb, NodeCopier& copier) const
 {
-	TrimNode* node = FB_NEW_POOL(*tdbb->getDefaultPool()) TrimNode(*tdbb->getDefaultPool(), where);
+	TrimNode* node = FB_NEW_POOL(*tdbb->getDefaultPool()) TrimNode(*tdbb->getDefaultPool(), where, what);
 	node->value = copier.copy(tdbb, value);
 	if (trimChars)
 		node->trimChars = copier.copy(tdbb, trimChars);
@@ -12800,9 +12801,13 @@ dsc* TrimNode::execute(thread_db* tdbb, Request* request) const
 
 	SLONG offsetLead = 0;
 	SLONG offsetTrail = valueCanonicalLen;
+	const bool multi = what == blr_trim_multi_characters;
 
 	// CVC: Avoid endless loop with zero length trim chars.
 	if (charactersCanonicalLen)
+	{
+		int charSize = charactersCanonical.getCount() / charactersLength;
+		if (!multi)
 		{
 			if (where == blr_trim_both || where == blr_trim_leading)
 			{
@@ -12832,6 +12837,55 @@ dsc* TrimNode::execute(thread_db* tdbb, Request* request) const
 				}
 			}
 		}
+		else
+		{
+			if (where == blr_trim_both || where == blr_trim_leading)
+			{
+				while (offsetLead < valueCanonicalLen)
+				{
+					bool found = false;
+					for (int i = 0; i < charactersCanonicalLen; i += charSize)
+					{
+						if (memcmp(&charactersCanonical[i],
+								   &valueCanonical[offsetLead],
+								   charSize) == 0)
+						{
+							found = true;
+							break;
+						}
+					}
+					if (!found)
+					{
+						break;
+					}
+					offsetLead += charSize;
+				}
+			}
+
+			if (where == blr_trim_both || where == blr_trim_trailing)
+			{
+				while (offsetTrail - charSize >= offsetLead)
+				{
+					bool found = false;
+					for (int i = 0; i < charactersCanonicalLen; i += charSize)
+					{
+						if (memcmp(&charactersCanonical[i],
+								   &valueCanonical[offsetTrail - charSize],
+								   charSize) == 0)
+						{
+							found = true;
+							break;
+						}
+					}
+					if (!found)
+					{
+						break;
+					}
+					offsetTrail -= charSize;
+				}
+			}
+		}
+	}
 
 	if (valueDesc->isBlob())
 	{

src/dsql/ExprNodes.h

@@ -2107,7 +2107,7 @@ public:
 class TrimNode final : public TypedNode<ValueExprNode, ExprNode::TYPE_TRIM>
 {
 public:
-	explicit TrimNode(MemoryPool& pool, UCHAR aWhere,
+	explicit TrimNode(MemoryPool& pool, UCHAR aWhere, UCHAR aWhat,
 		ValueExprNode* aValue = NULL, ValueExprNode* aTrimChars = NULL);
 
 	static DmlNode* parse(thread_db* tdbb, MemoryPool& pool, CompilerScratch* csb, const UCHAR blrOp);
@@ -2137,6 +2137,7 @@ public:
 
 public:
 	UCHAR where;
+	UCHAR what;
 	NestConst<ValueExprNode> value;
 	NestConst<ValueExprNode> trimChars;	// may be NULL
 };

src/dsql/parse.y

@@ -700,9 +700,12 @@ using namespace Firebird;
 // tokens added for Firebird 6.0
 
 %token <metaNamePtr> ANY_VALUE
+%token <metaNamePtr> BTRIM
 %token <metaNamePtr> CALL
 %token <metaNamePtr> FORMAT
+%token <metaNamePtr> LTRIM
 %token <metaNamePtr> NAMED_ARG_ASSIGN
+%token <metaNamePtr> RTRIM
 
 // precedence declarations for expression evaluation
 
@@ -4494,7 +4497,10 @@ keyword_or_column
 	| VARBINARY
 	| WINDOW
 	| WITHOUT
-	| CALL					// added in FB 6.0
+	| BTRIM					// added in FB 6.0
+	| CALL
+	| LTRIM
+	| RTRIM
 	;
 
 col_opt
@@ -8735,6 +8741,9 @@ of_first_last_day_part
 string_value_function
 	: substring_function
 	| trim_function
+	| btrim_function
+	| ltrim_function
+	| rtrim_function
 	| UPPER '(' value ')'
 		{ $$ = newNode<StrCaseNode>(blr_upcase, $3); }
 	| LOWER '(' value ')'
@@ -8766,13 +8775,13 @@ string_length_opt
 %type <valueExprNode> trim_function
 trim_function
 	: TRIM '(' trim_specification value FROM value ')'
-		{ $$ = newNode<TrimNode>($3, $6, $4); }
+		{ $$ = newNode<TrimNode>($3, blr_trim_characters, $6, $4); }
 	| TRIM '(' value FROM value ')'
-		{ $$ = newNode<TrimNode>(blr_trim_both, $5, $3); }
+		{ $$ = newNode<TrimNode>(blr_trim_both, blr_trim_characters, $5, $3); }
 	| TRIM '(' trim_specification FROM value ')'
-		{ $$ = newNode<TrimNode>($3, $5); }
+		{ $$ = newNode<TrimNode>($3, blr_trim_spaces, $5); }
 	| TRIM '(' value ')'
-		{ $$ = newNode<TrimNode>(blr_trim_both, $3); }
+		{ $$ = newNode<TrimNode>(blr_trim_both, blr_trim_spaces, $3); }
 	;
 
 %type <blrOp> trim_specification
@@ -8782,6 +8791,30 @@ trim_specification
 	| LEADING	{ $$ = blr_trim_leading; }
 	;
 
+%type <valueExprNode> btrim_function
+btrim_function
+	: BTRIM '(' value ',' value ')'
+		{ $$ = newNode<TrimNode>(blr_trim_both, blr_trim_multi_characters, $3, $5); }
+	| BTRIM '(' value ')'
+		{ $$ = newNode<TrimNode>(blr_trim_both, blr_trim_spaces, $3); }
+	;
+
+%type <valueExprNode> ltrim_function
+ltrim_function
+	: LTRIM '(' value ',' value ')'
+		{ $$ = newNode<TrimNode>(blr_trim_leading, blr_trim_multi_characters, $3, $5); }
+	| LTRIM '(' value ')'
+		{ $$ = newNode<TrimNode>(blr_trim_leading, blr_trim_spaces, $3); }
+	;
+
+%type <valueExprNode> rtrim_function
+rtrim_function
+	: RTRIM '(' value ',' value ')'
+		{ $$ = newNode<TrimNode>(blr_trim_trailing, blr_trim_multi_characters, $3, $5); }
+	| RTRIM '(' value ')'
+		{ $$ = newNode<TrimNode>(blr_trim_trailing, blr_trim_spaces, $3); }
+	;
+
 %type <valueExprNode> udf
 udf
 	: symbol_UDF_call_name '(' argument_list_opt ')'

src/include/firebird/impl/blr.h

@@ -345,6 +345,7 @@
 /* second sub parameter for blr_trim */
 #define blr_trim_spaces		(unsigned char)0
 #define blr_trim_characters	(unsigned char)1
+#define blr_trim_multi_characters (unsigned char)2
 
 /* These codes are actions for cursors */