gotype: initial commit of Go type abstraction

gotype.go

@@ -0,0 +1,59 @@
+package main
+
+type gotype struct {
+	SliceOf *gotype
+	MapKey  *gotype
+	MapVal  *gotype
+	PtrTo   *gotype
+	Plain   string
+	// TODO channel-of (although we will never? construct one from PHP source)
+}
+
+func (gt gotype) AsGoString() string {
+	if gt.SliceOf != nil {
+		return "[]" + gt.SliceOf.AsGoString()
+
+	} else if gt.MapKey != nil {
+		return "map[" + gt.MapKey.AsGoString() + "]" + gt.MapVal.AsGoString()
+
+	} else if gt.PtrTo != nil {
+		return "*" + gt.PtrTo.AsGoString()
+
+	} else {
+		return gt.Plain
+
+	}
+}
+
+// ZeroValue returns a Go literal string for the zero value of this type.
+func (gt gotype) ZeroValue() string {
+	if gt.SliceOf != nil || gt.MapKey != nil || gt.PtrTo != nil {
+		return `nil` // gt.AsGoString() + "{}"
+
+	}
+
+	// It's a plain type
+
+	switch gt.Plain {
+	case "byte",
+		"int", "int8", "int16", "int32", "int64",
+		"uint", "uint8", "uint16", "uint32", "uint64",
+		"float", "float64":
+		return `0`
+
+	case "bool":
+		return `false`
+
+	case "string":
+		return `""`
+
+	case "rune":
+		return `''`
+
+	default:
+		// probably a struct type
+		return gt.AsGoString() + `{}`
+
+	}
+
+}

node.go

@@ -253,7 +253,7 @@ func (this *conversionState) convertNoFreeFloating(n_ node.Node) (string, error)
 				// 'Modifiers' - protected public readonly ...
 				// prop.Modifiers
 
-				memberVars = append(memberVars, name+" "+memberType)
+				memberVars = append(memberVars, name+" "+memberType.AsGoString())
 
 			case *stmt.ClassConstList:
 				// Class constant
@@ -1471,7 +1471,7 @@ func removeParens(expr string) string {
 func (this *conversionState) resolveName(n node.Node) (string, error) {
 	// TODO support namespace lookups
 
-	ret := unknownVarType
+	ret := unknownVarType.AsGoString()
 	if n == nil || n == node.Node(nil) {
 		return ret, nil
 	}
@@ -1709,9 +1709,9 @@ func (this *conversionState) convertArrayLiteralCommon(items []node.Node) (strin
 	}
 
 	if isMapType {
-		return `map[` + keyType + `]` + valType + `{` + strings.Join(entries, " ") + `}`, nil
+		return `map[` + keyType.AsGoString() + `]` + valType.AsGoString() + `{` + strings.Join(entries, " ") + `}`, nil
 	} else {
-		return `[]` + valType + `{` + strings.Join(entries, " ") + `}`, nil
+		return `[]` + valType.AsGoString() + `{` + strings.Join(entries, " ") + `}`, nil
 	}
 }
 

scope.go

@@ -1,13 +1,13 @@
 package main
 
-const (
-	unknownVarType string = `unknown` // placeholder
-	mixedVarType   string = `mixed`   // when setting an incompatible type
+var (
+	unknownVarType gotype = gotype{Plain: `unknown`} // placeholder
+	mixedVarType   gotype = gotype{Plain: `mixed`}   // when setting an incompatible type
 )
 
 type LocalVar struct {
 	Name string
-	Type string
+	Type gotype
 }
 
 type Scope struct {
@@ -39,7 +39,7 @@ func (this *Scope) Has(varName string) *LocalVar {
 	return nil // not found
 }
 
-func (this *Scope) Set(Name, Type string) *LocalVar {
+func (this *Scope) Set(Name string, Type gotype) *LocalVar {
 
 	if lv := this.Has(Name); lv != nil {
 		// Update known type for existing variable