Parse switch expressions

parser/fspl/expression.go

@@ -117,6 +117,7 @@ func (this *treeParser) parseExpressionRootIdent () (entity.Expression, error) {
 	case "nil":           return this.parseLiteralNil()
 	case "if":            return this.parseIfElse()
 	case "match":         return this.parseMatch()
+	case "switch":        return this.parseSwitch()
 	case "loop":          return this.parseLoop()
 	case "for":           return this.parseFor()
 	default:
@@ -610,6 +611,49 @@ func (this *treeParser) parseMatchCase () (*entity.MatchCase, error) {
 	return cas, nil
 }
 
+func (this *treeParser) parseSwitch () (*entity.Switch, error) {
+	err := this.ExpectValue(lexer.Ident, "switch")
+	if err != nil { return nil, err }
+	switc := &entity.Switch {
+		Pos: this.Pos(),
+	}
+
+	err = this.ExpectNextDesc(descriptionExpression, startTokensExpression...)
+	if err != nil { return nil, err }
+	switc.Value, err = this.parseExpression()
+	if err != nil { return nil, err }
+
+	for this.Is(lexer.Symbol) && this.ValueIs("|") {
+		cas, err := this.parseSwitchCase()
+		if err != nil { return nil, err }
+		switc.Cases = append(switc.Cases, cas)
+	}
+
+	if this.Is(lexer.Star) {
+		defaul, err := this.parseDefaultCase()
+		if err != nil { return nil, err }
+		switc.Default = defaul
+	}
+
+	return switc, nil
+}
+
+func (this *treeParser) parseSwitchCase () (*entity.SwitchCase, error) {
+	err := this.ExpectValue(lexer.Symbol, "|")
+	if err != nil { return nil, err }
+	cas := &entity.SwitchCase {
+		Pos: this.Pos(),
+	}
+
+	this.Next()
+	cas.Key, err = this.parseExpression()
+	if err != nil { return nil, err }
+	cas.Expression, err = this.parseExpression()
+	if err != nil { return nil, err }
+	
+	return cas, nil
+}
+
 func (this *treeParser) parseDefaultCase () (*entity.DefaultCase, error) {
 	err := this.Expect(lexer.Star)
 	if err != nil { return nil, err }

parser/fspl/parser_test.go

@@ -74,7 +74,8 @@ testString (test,
 - [loop]:Int = {i:Int=0 if [< i 3] then return 1 loop {[print 3] if [> i 3] then break 0 i=[++ i]}}
 - [for s:String] = for i:Index e:Byte in str if [> i 3] then [break e]
 - [for s:String] = for e:Byte in s [break e]
-- [matchToInt u:(| Int F64)]:Int = match u | u:Int u | u:F64 [~ Int u] * 0`,
+- [matchToInt u:(| Int F64)]:Int = match u | u:Int u | u:F64 [~ Int u] * 0
+- [switch x:Int] = switch x | 0 5 | 1 4 | 2 3 * 0`,
 // input
 `
 [var]          = sdfdf
@@ -128,6 +129,11 @@ testString (test,
 	| u:Int u
 	| u:F64 [~Int u]
 	* 0
+[switch x:Int] = switch x
+	| 0 5
+	| 1 4
+	| 2 3
+	* 0
 `)
 }