新增: @use 同文件片段复用

支持 @use("name") 引用同一文件内 @tpl 定义的块，
消除 _list/_count 模板中 WHERE 条件重复问题。

internal/executor.go

@@ -15,6 +15,7 @@ type Executor struct {
 	style     PlaceholderStyle
 	rawPolicy rawValidator
 	strict    bool
+	blocks    map[string][]Node
 }
 
 type Result struct {
@@ -22,11 +23,12 @@ type Result struct {
 	Args []any
 }
 
-func NewExecutor(style PlaceholderStyle, rawPolicy rawValidator, strict bool) *Executor {
+func NewExecutor(style PlaceholderStyle, rawPolicy rawValidator, strict bool, blocks map[string][]Node) *Executor {
 	return &Executor{
 		style:     style,
 		rawPolicy: rawPolicy,
 		strict:    strict,
+		blocks:    blocks,
 	}
 }
 
@@ -99,6 +101,17 @@ func (e *Executor) walk(ctx *Context, ph *Placeholder, sql *strings.Builder, arg
 
 		case *BlockNode, *NamespaceNode, *IncludeNode, *CommentNode:
 			// skip
+		case *UseNode:
+			if e.blocks == nil {
+				return fmt.Errorf("line %d, col %d: @use(\"%s\") no blocks available", n.Pos.Line, n.Pos.Col, n.Name)
+			}
+			blockNodes, ok := e.blocks[n.Name]
+			if !ok {
+				return fmt.Errorf("line %d, col %d: @use(\"%s\") block not found", n.Pos.Line, n.Pos.Col, n.Name)
+			}
+			if err := e.walk(ctx, ph, sql, args, blockNodes); err != nil {
+				return err
+			}
 		}
 	}
 	return nil

internal/lexer.go

@@ -16,6 +16,7 @@ const (
 	TokTplStart
 	TokIncludeStart
 	TokNamespaceStart
+	TokUseStart
 	TokElse
 	TokComment
 	TokEOF
@@ -173,6 +174,7 @@ func (l *Lexer) tryDirective() (Token, bool) {
 		{[]rune("@tpl(\""), TokTplStart, 5},
 		{[]rune("@include(\""), TokIncludeStart, 10},
 		{[]rune("@namespace(\""), TokNamespaceStart, 12},
+		{[]rune("@use(\""), TokUseStart, 6},
 	}
 
 	for _, d := range directives {

internal/node.go

@@ -85,6 +85,13 @@ type CommentNode struct {
 
 func (n *CommentNode) nodeType() string { return "Comment" }
 
+type UseNode struct {
+	Pos  Pos
+	Name string
+}
+
+func (n *UseNode) nodeType() string { return "Use" }
+
 type ExprType int
 
 const (

internal/parser.go

@@ -96,6 +96,13 @@ func (p *Parser) Parse() ([]Node, error) {
 			}
 			nodes = append(nodes, node)
 
+			case TokUseStart:
+			node, err := p.parseUse(tok)
+			if err != nil {
+				return nil, err
+			}
+			nodes = append(nodes, node)
+
 		case TokElse:
 			return nil, fmt.Errorf("line %d, col %d: unexpected else", tok.Pos.Line, tok.Pos.Col)
 
@@ -521,6 +528,26 @@ func (p *Parser) expandInclude(tok Token) ([]Node, error) {
 	return subParser.Parse()
 }
 
+func (p *Parser) parseUse(tok Token) (*UseNode, error) {
+	runePos := p.runePosFromToken(tok)
+	name, quotePos, err := p.readUntilQuote(runePos)
+	if err != nil {
+		return nil, fmt.Errorf("line %d, col %d: unterminated @use name", tok.Pos.Line, tok.Pos.Col)
+	}
+	name = strings.TrimSpace(name)
+
+	endPos := quotePos + 1
+	if endPos < len(p.input) && p.input[endPos] == ')' {
+		endPos++
+	}
+	p.consumeTokensForRuneRange(runePos, endPos)
+
+	return &UseNode{
+		Pos:  tok.Pos,
+		Name: name,
+	}, nil
+}
+
 func (p *Parser) parseNamespace(tok Token, nodeCount int) (*NamespaceNode, error) {
 	if nodeCount > 0 {
 		return nil, fmt.Errorf("line %d, col %d: @namespace must be at the top of the file", tok.Pos.Line, tok.Pos.Col)
@@ -695,6 +722,12 @@ func (p *Parser) parseBlockBodyWithElse(blockType string) ([]Node, []Node, []*El
 				return nil, nil, nil, err
 			}
 			body = append(body, subNodes...)
+			case TokUseStart:
+			node, err := p.parseUse(tok)
+			if err != nil {
+				return nil, nil, nil, err
+			}
+			body = append(body, node)
 		case TokNamespaceStart:
 			return nil, nil, nil, fmt.Errorf("line %d, col %d: @namespace must be at file top level", tok.Pos.Line, tok.Pos.Col)
 		}