code review 4665041: Add the beginnings of the template execution code. Lot...

Add the beginnings of the template execution code.  Lots still to do,
including evaluation up the data tree (in this code all fields must be
in dot itself), plus more control structure, but the basics are in place.

[r, 2011-06-28 10:55:40]

Hello rsc@golang.org (cc: golang-dev@googlegroups.com),

I'd like you to review this change to
https://go.googlecode.com/hg/

[rsc, 2011-06-28 12:04:01]

LGTM

Does the pipeline stuff subsume the current formatter map?
(Could hang formatting methods on the top-level piece of data,
as long as they return []byte or string or something.)

http://codereview.appspot.com/4665041/diff/8001/src/pkg/exp/template/exec.go
File src/pkg/exp/template/exec.go (right):

http://codereview.appspot.com/4665041/diff/8001/src/pkg/exp/template/exec.go#...
src/pkg/exp/template/exec.go:17: // template so that mulitple executions of the
same template
s/mulitple/multiple/

http://codereview.appspot.com/4665041/diff/8001/src/pkg/exp/template/exec.go#...
src/pkg/exp/template/exec.go:57: case nil:
Can this really happen?  If so comment how.

http://codereview.appspot.com/4665041/diff/8001/src/pkg/exp/template/exec.go#...
src/pkg/exp/template/exec.go:77: func (s *state) walkRange(data reflect.Value, r
*rangeNode) {
I assume if is coming.

http://codereview.appspot.com/4665041/diff/8001/src/pkg/exp/template/exec.go#...
src/pkg/exp/template/exec.go:93: s.walk(key, r.list)
The old template package walks val.MapIndex(key) here.
It might be nice to be able to have access to both, but the
value seems more important if you only have one (and more
in keeping with the array loop).

http://codereview.appspot.com/4665041/diff/8001/src/pkg/exp/template/exec.go#...
src/pkg/exp/template/exec.go:140: func (s *state) exported(name string) {
Delete

http://codereview.appspot.com/4665041/diff/8001/src/pkg/exp/template/exec.go#...
src/pkg/exp/template/exec.go:158: if field.IsValid() {
if field.IsValid() && field.PkgPath == "" {  // valid and not exported
    return field
}

An unexported field should be missing, so that the
look higher up the tree can still get a chance (for map
keys, etc).

http://codereview.appspot.com/4665041/diff/8001/src/pkg/exp/template/exec.go#...
src/pkg/exp/template/exec.go:165: s.errorf("can't handle evaluation of field %s
of  type %s", fieldName, data.Type())
s/  / /
s/handle evaluation of/evaluate/g

http://codereview.appspot.com/4665041/diff/8001/src/pkg/exp/template/exec.go#...
src/pkg/exp/template/exec.go:170: func (s *state) evalFieldOrMethod(data
reflect.Value, fieldName string, args []node, final reflect.Value) reflect.Value
{
really evalMethodOrField

http://codereview.appspot.com/4665041/diff/8001/src/pkg/exp/template/exec.go#...
src/pkg/exp/template/exec.go:172: for {
for data.Kind() == reflect.Ptr {

http://codereview.appspot.com/4665041/diff/8001/src/pkg/exp/template/exec.go#...
src/pkg/exp/template/exec.go:181: // Is it a method? We use the pointer because
it has value methods too.
Move up outside the switch data.Kind() ?

http://codereview.appspot.com/4665041/diff/8001/src/pkg/exp/template/exec.go#...
src/pkg/exp/template/exec.go:200: osErrorType =
reflect.ValueOf(new(os.Error)).Elem().Type()
osErrorType = reflect.TypeOf(new(os.Error)).Elem()

http://codereview.appspot.com/4665041/diff/8001/src/pkg/exp/template/exec.go#...
src/pkg/exp/template/exec.go:207: if typ.IsVariadic() {
Call will handle the variadic stuff.
This code only needs to tweak the numIn check.

if !typ.IsVariadic && numIn < typ.NumIn()-1 || !typ.IsVariadic() && numIn !=
typ.NumIn() {

http://codereview.appspot.com/4665041/diff/8001/src/pkg/exp/template/exec.go#...
src/pkg/exp/template/exec.go:269: func (s *state) evalString(v reflect.Value,
typ reflect.Type, n node) reflect.Value {
Missing evalBool.

[r2, 2011-06-28 12:21:48]

On Jun 28, 2011, at 10:04 PM, rsc@golang.org wrote:

> LGTM
> 
> Does the pipeline stuff subsume the current formatter map?
> (Could hang formatting methods on the top-level piece of data,
> as long as they return []byte or string or something.)

that's the plan.

-rob

[r, 2011-06-28 13:04:18]

*** Submitted as http://code.google.com/p/go/source/detail?r=632f57713423 ***

Add the beginnings of the template execution code.  Lots still to do,
including evaluation up the data tree (in this code all fields must be
in dot itself), plus more control structure, but the basics are in place.

R=rsc, r
CC=golang-dev
http://codereview.appspot.com/4665041