Add parser features and enable 15 more tests

CLAUDE.md

@@ -60,3 +60,7 @@ Each test in `parser/testdata/` contains:
 - `metadata.json` - `{"skip": true}` or `{"skip": false}`
 - `query.sql` - T-SQL to parse
 - `ast.json` - Expected AST output
+
+## Important Rules
+
+- **NEVER modify `ast.json` files** - These are golden files containing the expected output. If tests fail due to JSON mismatches, fix the Go code to match the expected output, not the other way around.

ast/select_set_variable.go

@@ -0,0 +1,12 @@
+package ast
+
+// SelectSetVariable represents a variable assignment in a SELECT statement.
+// Example: SELECT @a = 1, @b ||= 'foo'
+type SelectSetVariable struct {
+	Variable       *VariableReference `json:"Variable,omitempty"`
+	Expression     ScalarExpression   `json:"Expression,omitempty"`
+	AssignmentKind string             `json:"AssignmentKind,omitempty"`
+}
+
+func (*SelectSetVariable) node()          {}
+func (*SelectSetVariable) selectElement() {}

ast/workload_classifier_statement.go

@@ -0,0 +1,87 @@
+// Package ast provides AST types for T-SQL parsing.
+package ast
+
+// CreateWorkloadClassifierStatement represents a CREATE WORKLOAD CLASSIFIER statement.
+type CreateWorkloadClassifierStatement struct {
+	ClassifierName *Identifier
+	Options        []WorkloadClassifierOption
+}
+
+func (s *CreateWorkloadClassifierStatement) statement() {}
+func (s *CreateWorkloadClassifierStatement) node()      {}
+
+// WorkloadClassifierOption is the interface for workload classifier options.
+type WorkloadClassifierOption interface {
+	node()
+	workloadClassifierOption()
+}
+
+// ClassifierWorkloadGroupOption represents the WORKLOAD_GROUP option.
+type ClassifierWorkloadGroupOption struct {
+	WorkloadGroupName *StringLiteral
+	OptionType        string
+}
+
+func (o *ClassifierWorkloadGroupOption) node()                     {}
+func (o *ClassifierWorkloadGroupOption) workloadClassifierOption() {}
+
+// ClassifierMemberNameOption represents the MEMBERNAME option.
+type ClassifierMemberNameOption struct {
+	MemberName *StringLiteral
+	OptionType string
+}
+
+func (o *ClassifierMemberNameOption) node()                     {}
+func (o *ClassifierMemberNameOption) workloadClassifierOption() {}
+
+// ClassifierWlmContextOption represents the WLM_CONTEXT option.
+type ClassifierWlmContextOption struct {
+	WlmContext *StringLiteral
+	OptionType string
+}
+
+func (o *ClassifierWlmContextOption) node()                     {}
+func (o *ClassifierWlmContextOption) workloadClassifierOption() {}
+
+// WlmTimeLiteral represents a time literal for WLM START_TIME/END_TIME options.
+type WlmTimeLiteral struct {
+	TimeString *StringLiteral
+}
+
+func (t *WlmTimeLiteral) node() {}
+
+// ClassifierStartTimeOption represents the START_TIME option.
+type ClassifierStartTimeOption struct {
+	Time       *WlmTimeLiteral
+	OptionType string
+}
+
+func (o *ClassifierStartTimeOption) node()                     {}
+func (o *ClassifierStartTimeOption) workloadClassifierOption() {}
+
+// ClassifierEndTimeOption represents the END_TIME option.
+type ClassifierEndTimeOption struct {
+	Time       *WlmTimeLiteral
+	OptionType string
+}
+
+func (o *ClassifierEndTimeOption) node()                     {}
+func (o *ClassifierEndTimeOption) workloadClassifierOption() {}
+
+// ClassifierWlmLabelOption represents the WLM_LABEL option.
+type ClassifierWlmLabelOption struct {
+	WlmLabel   *StringLiteral
+	OptionType string
+}
+
+func (o *ClassifierWlmLabelOption) node()                     {}
+func (o *ClassifierWlmLabelOption) workloadClassifierOption() {}
+
+// ClassifierImportanceOption represents the IMPORTANCE option.
+type ClassifierImportanceOption struct {
+	Importance string
+	OptionType string
+}
+
+func (o *ClassifierImportanceOption) node()                     {}
+func (o *ClassifierImportanceOption) workloadClassifierOption() {}

parser/lexer.go

@@ -85,6 +85,19 @@ const (
 	TokenRBrace
 	TokenLeftShift
 	TokenRightShift
+	TokenPipe           // |
+	TokenDoublePipe     // ||
+	TokenConcatEquals   // ||=
+	TokenBitwiseAnd     // &
+	TokenPlusEquals     // +=
+	TokenMinusEquals    // -=
+	TokenStarEquals     // *=
+	TokenSlashEquals    // /=
+	TokenModuloEquals   // %=
+	TokenAndEquals      // &=
+	TokenOrEquals       // |=
+	TokenXorEquals      // ^=
+	TokenCaret          // ^
 
 	// DML Keywords
 	TokenInsert
@@ -265,9 +278,16 @@ func (l *Lexer) NextToken() Token {
 		tok.Type = TokenEOF
 		tok.Literal = ""
 	case '*':
-		tok.Type = TokenStar
-		tok.Literal = "*"
-		l.readChar()
+		if l.peekChar() == '=' {
+			l.readChar()
+			tok.Type = TokenStarEquals
+			tok.Literal = "*="
+			l.readChar()
+		} else {
+			tok.Type = TokenStar
+			tok.Literal = "*"
+			l.readChar()
+		}
 	case ',':
 		tok.Type = TokenComma
 		tok.Literal = ","
@@ -355,21 +375,94 @@ func (l *Lexer) NextToken() Token {
 		tok.Literal = "}"
 		l.readChar()
 	case '+':
-		tok.Type = TokenPlus
-		tok.Literal = "+"
-		l.readChar()
+		if l.peekChar() == '=' {
+			l.readChar()
+			tok.Type = TokenPlusEquals
+			tok.Literal = "+="
+			l.readChar()
+		} else {
+			tok.Type = TokenPlus
+			tok.Literal = "+"
+			l.readChar()
+		}
 	case '-':
-		tok.Type = TokenMinus
-		tok.Literal = "-"
-		l.readChar()
+		if l.peekChar() == '=' {
+			l.readChar()
+			tok.Type = TokenMinusEquals
+			tok.Literal = "-="
+			l.readChar()
+		} else {
+			tok.Type = TokenMinus
+			tok.Literal = "-"
+			l.readChar()
+		}
 	case '/':
-		tok.Type = TokenSlash
-		tok.Literal = "/"
-		l.readChar()
+		if l.peekChar() == '=' {
+			l.readChar()
+			tok.Type = TokenSlashEquals
+			tok.Literal = "/="
+			l.readChar()
+		} else {
+			tok.Type = TokenSlash
+			tok.Literal = "/"
+			l.readChar()
+		}
 	case '%':
-		tok.Type = TokenModulo
-		tok.Literal = "%"
-		l.readChar()
+		if l.peekChar() == '=' {
+			l.readChar()
+			tok.Type = TokenModuloEquals
+			tok.Literal = "%="
+			l.readChar()
+		} else {
+			tok.Type = TokenModulo
+			tok.Literal = "%"
+			l.readChar()
+		}
+	case '|':
+		if l.peekChar() == '|' {
+			l.readChar() // consume first |
+			if l.peekChar() == '=' {
+				l.readChar() // consume second |
+				tok.Type = TokenConcatEquals
+				tok.Literal = "||="
+				l.readChar() // consume =
+			} else {
+				tok.Type = TokenDoublePipe
+				tok.Literal = "||"
+				l.readChar() // consume second |
+			}
+		} else if l.peekChar() == '=' {
+			l.readChar()
+			tok.Type = TokenOrEquals
+			tok.Literal = "|="
+			l.readChar()
+		} else {
+			tok.Type = TokenPipe
+			tok.Literal = "|"
+			l.readChar()
+		}
+	case '&':
+		if l.peekChar() == '=' {
+			l.readChar()
+			tok.Type = TokenAndEquals
+			tok.Literal = "&="
+			l.readChar()
+		} else {
+			tok.Type = TokenBitwiseAnd
+			tok.Literal = "&"
+			l.readChar()
+		}
+	case '^':
+		if l.peekChar() == '=' {
+			l.readChar()
+			tok.Type = TokenXorEquals
+			tok.Literal = "^="
+			l.readChar()
+		} else {
+			tok.Type = TokenCaret
+			tok.Literal = "^"
+			l.readChar()
+		}
 	case '\'':
 		tok = l.readString()
 	default: