reflection support for tag strings

R=rsc
DELTA=86  (77 added, 0 deleted, 9 changed)
OCL=18201
CL=18203

src/lib/reflect/test.go

@@ -118,6 +118,8 @@ func main() {
 	typedump("struct {a int8; b int8; c int8; b int32}", "struct{a int8; b int8; c int8; b int32}");
 	typedump("struct {a int8; b int8; c int8; d int8; b int32}", "struct{a int8; b int8; c int8; d int8; b int32}");
 	typedump("struct {a int8; b int8; c int8; d int8; e int8; b int32}", "struct{a int8; b int8; c int8; d int8; e int8; b int32}");
+	typedump("struct {a int8 \"hi there\"; }", "struct{a int8 \"hi there\"}");
+	typedump("struct {a int8 \"hi \\0there\\t\\n\\\"\\\\\"; }", "struct{a int8 \"hi \\0there\\t\\n\\\"\\\\\"}");
 
 	valuedump("int8", "8");
 	valuedump("int16", "16");

src/lib/reflect/tostring.go

@@ -15,16 +15,42 @@ import (
 export func TypeToString(typ Type, expand bool) string
 export func ValueToString(val Value) string
 
+func DoubleQuote(s string) string {
+	out := "\"";
+	for i := 0; i < len(s); i++ {
+		c := s[i];
+		switch c {
+		case '\n':
+			out += `\n`;
+		case '\t':
+			out += `\t`;
+		case '\x00':
+			out += `\0`;
+		case '"':
+			out += `\"`;
+		case '\\':
+			out += `\\`;
+		default:
+			out += string(c);
+		}
+	}
+	out += "\"";
+	return out;
+}
+
 type HasFields interface {
-	Field(i int)	(name string, typ Type, offset uint64);
+	Field(i int)	(name string, typ Type, tag string, offset uint64);
 	Len()	int;
 }
 
 func TypeFieldsToString(t HasFields, sep string) string {
 	var str string;
 	for i := 0; i < t.Len(); i++ {
-		str1, typ, offset := t.Field(i);
+		str1, typ, tag, offset := t.Field(i);
 		str1 +=  " " + TypeToString(typ, false);
+		if tag != "" {
+			str1 += " " + DoubleQuote(tag);
+		}
 		if i < t.Len() - 1 {
 			str1 += sep + " ";
 		}

src/lib/reflect/type.go

@@ -245,13 +245,14 @@ func (t *ChanTypeStruct) Elem() Type {
 // -- Struct
 
 export type StructType interface {
-	Field(int)	(name string, typ Type, offset uint64);
+	Field(int)	(name string, typ Type, tag string, offset uint64);
 	Len()	int;
 }
 
 type Field struct {
 	name	string;
 	typ	*StubType;
+	tag	string;
 	size	uint64;
 	offset	uint64;
 }
@@ -289,11 +290,11 @@ func (t *StructTypeStruct) Size() uint64 {
 	return size;
 }
 
-func (t *StructTypeStruct) Field(i int) (name string, typ Type, offset uint64) {
+func (t *StructTypeStruct) Field(i int) (name string, typ Type, tag string, offset uint64) {
 	if t.field[i].offset == 0 {
 		t.Size();	// will compute offsets
 	}
-	return t.field[i].name, t.field[i].typ.Get(), t.field[i].offset
+	return t.field[i].name, t.field[i].typ.Get(), t.field[i].tag, t.field[i].offset
 }
 
 func (t *StructTypeStruct) Len() int {
@@ -303,7 +304,7 @@ func (t *StructTypeStruct) Len() int {
 // -- Interface
 
 export type InterfaceType interface {
-	Field(int)	(name string, typ Type, offset uint64);
+	Field(int)	(name string, typ Type, tag string, offset uint64);
 	Len()	int;
 }
 
@@ -316,8 +317,8 @@ func NewInterfaceTypeStruct(name string, field *[]Field) *InterfaceTypeStruct {
 	return &InterfaceTypeStruct{ Common{InterfaceKind, name, interfacesize}, field }
 }
 
-func (t *InterfaceTypeStruct) Field(i int) (name string, typ Type, offset uint64) {
-	return t.field[i].name, t.field[i].typ.Get(), 0
+func (t *InterfaceTypeStruct) Field(i int) (name string, typ Type, tag string, offset uint64) {
+	return t.field[i].name, t.field[i].typ.Get(), "", 0
 }
 
 func (t *InterfaceTypeStruct) Len() int {
@@ -489,6 +490,33 @@ func special(c uint8) bool {
 	return false;
 }
 
+// Process backslashes.  String known to be well-formed.
+// Initial double-quote is left in, as an indication this token is a string.
+func unescape(s string, backslash bool) string {
+	if !backslash {
+		return s
+	}
+	out := "\"";
+	for i := 1; i < len(s); i++ {
+		c := s[i];
+		if c == '\\' {
+			i++;
+			c = s[i];
+			switch c {
+			case 'n':
+				c = '\n';
+			case 't':
+				c = '\t';
+			case '0':	// it's not a legal go string but \0 means NUL
+				c = '\x00';
+			// default is correct already; \\ is \; \" is "
+			}
+		}
+		out += string(c);
+	}
+	return out;
+}
+
 // Simple parser for type strings
 type Parser struct {
 	str	string;	// string being parsed
@@ -525,6 +553,23 @@ func (p *Parser) Next() {
 		}
 		p.token = p.str[start : p.index];
 		return;
+	case c == '"':	// double-quoted string for struct field annotation
+		backslash := false;
+		for p.index < len(p.str) && p.str[p.index] != '"' {
+			if p.str[p.index] == '\\' {
+				if p.index+1 == len(p.str) {	// bad final backslash
+					break;
+				}
+				p.index++;	// skip (and accept) backslash
+				backslash = true;
+			}
+			p.index++
+		}
+		p.token = unescape(p.str[start : p.index], backslash);
+		if p.index < len(p.str) {	// properly terminated string
+			p.index++;	// skip the terminating double-quote
+		}
+		return;
 	}
 	for p.index < len(p.str) && p.str[p.index] != ' ' && !special(p.str[p.index]) {
 		p.index++
@@ -598,6 +643,10 @@ func (p *Parser) Fields(sep string) *[]Field {
 		a[nf].name = p.token;
 		p.Next();
 		a[nf].typ = p.Type("");
+		if p.token != "" && p.token[0] == '"' {
+			a[nf].tag = p.token[1:len(p.token)];
+			p.Next();
+		}
 		nf++;
 		if p.token != sep {
 			break;

src/lib/reflect/value.go

@@ -609,7 +609,7 @@ func StructCreator(typ Type, addr Addr) Value {
 	nfield := t.Len();
 	v := &StructValueStruct{ CommonV{StructKind, typ, addr}, new([]Value, nfield) };
 	for i := 0; i < nfield; i++ {
-		name, ftype, offset := t.Field(i);
+		name, ftype, str, offset := t.Field(i);
 		v.field[i] = NewValueAddr(ftype, addr + offset);
 	}
 	v.typ = typ;