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Simplified AST:

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- one node for array and slice types
- one node for index and slice expressions
- simplified parser, astprinter, and ast.txt

R=r
DELTA=71  (0 added, 43 deleted, 28 changed)
OCL=28768
CL=28768
This commit is contained in:
Robert Griesemer 2009-05-13 15:18:05 -07:00
parent 6fa6f134f1
commit f3b08744a2
4 changed files with 26 additions and 69 deletions
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26
src/lib/go/ast/ast.go
View File

@ -204,16 +204,11 @@ type (
Sel *Ident; // field selector
};
// An IndexExpr node represents an expression followed by an index.
// An IndexExpr node represents an expression followed by an index or slice.
IndexExpr struct {
X Expr; // expression
Index Expr; // index expression
};
// A SliceExpr node represents an expression followed by a slice.
SliceExpr struct {
X Expr; // expression
Begin, End Expr; // slice range
Index Expr; // index expression or beginning of slice range
End Expr; // end of slice range; or nil
};
// A TypeAssertExpr node represents an expression followed by a
@ -283,16 +278,10 @@ const (
// nodes.
//
type (
// An ArrayType node represents an array type.
// An ArrayType node represents an array or slice type.
ArrayType struct {
token.Position; // position of "["
Len Expr; // possibly an Ellipsis node for [...]T array types
Elt Expr; // element type
};
// A SliceType node represents a slice type.
SliceType struct {
token.Position; // position of "["
Len Expr; // Ellipsis node for [...]T array types, nil for slice types
Elt Expr; // element type
};
@ -345,7 +334,6 @@ func (x *FuncLit) Pos() token.Position { return x.Type.Pos(); }
func (x *CompositeLit) Pos() token.Position { return x.Type.Pos(); }
func (x *SelectorExpr) Pos() token.Position { return x.X.Pos(); }
func (x *IndexExpr) Pos() token.Position { return x.X.Pos(); }
func (x *SliceExpr) Pos() token.Position { return x.X.Pos(); }
func (x *TypeAssertExpr) Pos() token.Position { return x.X.Pos(); }
func (x *CallExpr) Pos() token.Position { return x.Fun.Pos(); }
func (x *BinaryExpr) Pos() token.Position { return x.X.Pos(); }
@ -371,7 +359,6 @@ type ExprVisitor interface {
DoParenExpr(x *ParenExpr);
DoSelectorExpr(x *SelectorExpr);
DoIndexExpr(x *IndexExpr);
DoSliceExpr(x *SliceExpr);
DoTypeAssertExpr(x *TypeAssertExpr);
DoCallExpr(x *CallExpr);
DoStarExpr(x *StarExpr);
@ -382,7 +369,6 @@ type ExprVisitor interface {
// Type expressions
DoEllipsis(x *Ellipsis);
DoArrayType(x *ArrayType);
DoSliceType(x *SliceType);
DoStructType(x *StructType);
DoFuncType(x *FuncType);
DoInterfaceType(x *InterfaceType);
@ -406,7 +392,6 @@ func (x *CompositeLit) Visit(v ExprVisitor) { v.DoCompositeLit(x); }
func (x *ParenExpr) Visit(v ExprVisitor) { v.DoParenExpr(x); }
func (x *SelectorExpr) Visit(v ExprVisitor) { v.DoSelectorExpr(x); }
func (x *IndexExpr) Visit(v ExprVisitor) { v.DoIndexExpr(x); }
func (x *SliceExpr) Visit(v ExprVisitor) { v.DoSliceExpr(x); }
func (x *TypeAssertExpr) Visit(v ExprVisitor) { v.DoTypeAssertExpr(x); }
func (x *CallExpr) Visit(v ExprVisitor) { v.DoCallExpr(x); }
func (x *StarExpr) Visit(v ExprVisitor) { v.DoStarExpr(x); }
@ -415,7 +400,6 @@ func (x *BinaryExpr) Visit(v ExprVisitor) { v.DoBinaryExpr(x); }
func (x *KeyValueExpr) Visit(v ExprVisitor) { v.DoKeyValueExpr(x); }
func (x *ArrayType) Visit(v ExprVisitor) { v.DoArrayType(x); }
func (x *SliceType) Visit(v ExprVisitor) { v.DoSliceType(x); }
func (x *StructType) Visit(v ExprVisitor) { v.DoStructType(x); }
func (x *FuncType) Visit(v ExprVisitor) { v.DoFuncType(x); }
func (x *InterfaceType) Visit(v ExprVisitor) { v.DoInterfaceType(x); }

26
src/lib/go/parser/parser.go
View File

@ -330,9 +330,9 @@ func (p *parser) parseTypeName() ast.Expr {
}
func (p *parser) parseArrayOrSliceType(ellipsis_ok bool) ast.Expr {
func (p *parser) parseArrayType(ellipsis_ok bool) ast.Expr {
if p.trace {
defer un(trace(p, "ArrayOrSliceType"));
defer un(trace(p, "ArrayType"));
}
lbrack := p.expect(token.LBRACK);
@ -346,11 +346,7 @@ func (p *parser) parseArrayOrSliceType(ellipsis_ok bool) ast.Expr {
p.expect(token.RBRACK);
elt := p.parseType();
if len != nil {
return &ast.ArrayType{lbrack, len, elt};
}
return &ast.SliceType{lbrack, elt};
return &ast.ArrayType{lbrack, len, elt};
}
@ -713,7 +709,7 @@ func (p *parser) parseChanType() *ast.ChanType {
func (p *parser) tryRawType(ellipsis_ok bool) ast.Expr {
switch p.tok {
case token.IDENT: return p.parseTypeName();
case token.LBRACK: return p.parseArrayOrSliceType(ellipsis_ok);
case token.LBRACK: return p.parseArrayType(ellipsis_ok);
case token.STRUCT: return p.parseStructType();
case token.MUL: return p.parsePointerType();
case token.FUNC: return p.parseFuncType();
@ -921,9 +917,9 @@ func (p *parser) parseSelectorOrTypeAssertion(x ast.Expr) ast.Expr {
}
func (p *parser) parseIndexOrSlice(x ast.Expr) ast.Expr {
func (p *parser) parseIndex(x ast.Expr) ast.Expr {
if p.trace {
defer un(trace(p, "IndexOrSlice"));
defer un(trace(p, "Index"));
}
p.expect(token.LBRACK);
@ -937,11 +933,7 @@ func (p *parser) parseIndexOrSlice(x ast.Expr) ast.Expr {
p.expr_lev--;
p.expect(token.RBRACK);
if end != nil {
return &ast.SliceExpr{x, begin, end};
}
return &ast.IndexExpr{x, begin};
return &ast.IndexExpr{x, begin, end};
}
@ -1059,7 +1051,6 @@ func (p *parser) checkExpr(x ast.Expr) ast.Expr {
case *ast.ParenExpr:
case *ast.SelectorExpr:
case *ast.IndexExpr:
case *ast.SliceExpr:
case *ast.TypeAssertExpr:
case *ast.CallExpr:
case *ast.StarExpr:
@ -1105,7 +1096,6 @@ func (p *parser) checkCompositeLitType(x ast.Expr) ast.Expr {
case *ast.ParenExpr: p.checkCompositeLitType(t.X);
case *ast.SelectorExpr: p.checkTypeName(t.X);
case *ast.ArrayType: return x;
case *ast.SliceType: return x;
case *ast.StructType: return x;
case *ast.MapType: return x;
default:
@ -1150,7 +1140,7 @@ func (p *parser) parsePrimaryExpr() ast.Expr {
for {
switch p.tok {
case token.PERIOD: x = p.parseSelectorOrTypeAssertion(p.checkExpr(x));
case token.LBRACK: x = p.parseIndexOrSlice(p.checkExpr(x));
case token.LBRACK: x = p.parseIndex(p.checkExpr(x));
case token.LPAREN: x = p.parseCallOrConversion(p.checkExprOrType(x));
case token.LBRACE:
if p.expr_lev >= 0 {

18
usr/gri/pretty/ast.txt
View File

@ -5,7 +5,7 @@
// Format file for printing AST nodes (package "ast").
// ----------------------------------------------------------------------------
// Debugging
// Elementary types
token.Token =
^:string;
@ -25,11 +25,11 @@ char =
bytes =
{*};
nil =
; // TODO we see a lot of nil's - why?
empty =
;
exists =
*:nil;
*:empty;
// ----------------------------------------------------------------------------
@ -98,10 +98,7 @@ ast.SelectorExpr =
X "." Sel;
ast.IndexExpr =
X "[" Index "]";
ast.SliceExpr =
X "[" Begin ":" End "]";
X "[" Index [":" End] "]";
ast.TypeAssertExpr =
X ".(" Type ")";
@ -122,10 +119,7 @@ ast.KeyValueExpr =
Key ": " Value;
ast.ArrayType =
"[" Len "]" Elt;
ast.SliceType =
"[]" Elt;
"[" [Len] "]" Elt;
ast.StructType =
"struct"

25
usr/gri/pretty/astprinter.go
View File

@ -735,16 +735,10 @@ func (P *Printer) DoIndexExpr(x *ast.IndexExpr) {
P.Expr1(x.X, token.HighestPrec);
P.Token(noPos, token.LBRACK);
P.Expr(x.Index);
P.Token(noPos, token.RBRACK);
}
func (P *Printer) DoSliceExpr(x *ast.SliceExpr) {
P.Expr1(x.X, token.HighestPrec);
P.Token(noPos, token.LBRACK);
P.Expr(x.Begin);
P.Token(noPos, token.COLON);
P.Expr(x.End);
if x.End != nil {
P.Token(noPos, token.COLON);
P.Expr(x.End);
}
P.Token(noPos, token.RBRACK);
}
@ -772,14 +766,9 @@ func (P *Printer) DoEllipsis(x *ast.Ellipsis) {
func (P *Printer) DoArrayType(x *ast.ArrayType) {
P.Token(x.Pos(), token.LBRACK);
P.Expr(x.Len);
P.Token(noPos, token.RBRACK);
P.Expr(x.Elt);
}
func (P *Printer) DoSliceType(x *ast.SliceType) {
P.Token(x.Pos(), token.LBRACK);
if x.Len != nil {
P.Expr(x.Len);
}
P.Token(noPos, token.RBRACK);
P.Expr(x.Elt);
}