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text/template: revert CL 66410 "add break, continue actions in ranges" 

The new break and continue actions do not work in html/template, and
fixing them requires thinking about security issues that seem too
tricky at this stage of the release. We will try again for 1.11.

Original CL description:

    text/template: add break, continue actions in ranges

    Adds the two range control actions "break" and "continue". They act the
    same as the Go keywords break and continue, but are simplified in that
    only the innermost range statement can be broken out of or continued.

    Fixes #20531

Updates #20531
Updates #23683

Change-Id: Ia7fd3c409163e3bcb5dc42947ae90b15bdf89853
Reviewed-on: https://go-review.googlesource.com/92155
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
changes/55/92155/3
Ian Lance Taylor 2018-02-05 15:50:29 -08:00
parent f54f780d2f
commit fd7331a821
10 changed files with 31 additions and 225 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
api/go1.10.txt
View File

@ -618,24 +618,6 @@ pkg syscall (windows-386), func CreateProcessAsUser(Token, *uint16, *uint16, *Se
pkg syscall (windows-386), type SysProcAttr struct, Token Token
pkg syscall (windows-amd64), func CreateProcessAsUser(Token, *uint16, *uint16, *SecurityAttributes, *SecurityAttributes, bool, uint32, *uint16, *uint16, *StartupInfo, *ProcessInformation) error
pkg syscall (windows-amd64), type SysProcAttr struct, Token Token
pkg text/template/parse, const NodeBreak = 20
pkg text/template/parse, const NodeBreak NodeType
pkg text/template/parse, const NodeContinue = 21
pkg text/template/parse, const NodeContinue NodeType
pkg text/template/parse, method (*BreakNode) Copy() Node
pkg text/template/parse, method (*BreakNode) Position() Pos
pkg text/template/parse, method (*BreakNode) String() string
pkg text/template/parse, method (*BreakNode) Type() NodeType
pkg text/template/parse, method (*ContinueNode) Copy() Node
pkg text/template/parse, method (*ContinueNode) Position() Pos
pkg text/template/parse, method (*ContinueNode) String() string
pkg text/template/parse, method (*ContinueNode) Type() NodeType
pkg text/template/parse, type BreakNode struct
pkg text/template/parse, type BreakNode struct, embedded NodeType
pkg text/template/parse, type BreakNode struct, embedded Pos
pkg text/template/parse, type ContinueNode struct
pkg text/template/parse, type ContinueNode struct, embedded NodeType
pkg text/template/parse, type ContinueNode struct, embedded Pos
pkg time, func LoadLocationFromTZData(string, []uint8) (*Location, error)
pkg unicode, const Version = "10.0.0"
pkg unicode, var Masaram_Gondi *RangeTable

14
doc/go1.10.html
View File

@ -1069,11 +1069,6 @@ now implement those interfaces.
<dl id="html/template"><dt><a href="/pkg/html/template/">html/template</a></dt>
<dd>
<p>
The new actions <code>{{"{{break}}"}}</code> and <code>{{"{{continue}}"}}</code>
break out of the innermost <code>{{"{{range"}}</code>&nbsp;...<code>}}</code> loop,
like the corresponding Go statements.
</p>
<p>
The new <a href="/pkg/html/template#Srcset"><code>Srcset</code></a> content
type allows for proper handling of values within the
<a href="https://w3c.github.io/html/semantics-embedded-content.html#element-attrdef-img-srcset"><code>srcset</code></a>
@ -1411,15 +1406,6 @@ is now implemented.
</p>
</dl>
<dl id="text/template"><dt><a href="/pkg/text/template/">text/template</a></dt>
<dd>
<p>
The new actions <code>{{"{{break}}"}}</code> and <code>{{"{{continue}}"}}</code>
break out of the innermost <code>{{"{{range"}}</code>&nbsp;...<code>}}</code> loop,
like the corresponding Go statements.
</p>
</dl>
<dl id="time"><dt><a href="/pkg/time/">time</a></dt>
<dd>
<p>

6
src/text/template/doc.go
View File

@ -110,12 +110,6 @@ data, defined in detail in the corresponding sections that follow.
T0 is executed; otherwise, dot is set to the successive elements
of the array, slice, or map and T1 is executed.
{{break}}
Break out of the surrounding range loop.
{{continue}}
Begin the next iteration of the surrounding range loop.
{{template "name"}}
The template with the specified name is executed with nil data.

84
src/text/template/exec.go
View File

@ -25,12 +25,11 @@ const maxExecDepth = 100000
// template so that multiple executions of the same template
// can execute in parallel.
type state struct {
tmpl *Template
wr io.Writer
node parse.Node // current node, for errors.
vars []variable // push-down stack of variable values.
depth int // the height of the stack of executing templates.
rangeDepth int // nesting level of range loops.
tmpl *Template
wr io.Writer
node parse.Node // current node, for errors
vars []variable // push-down stack of variable values.
depth int // the height of the stack of executing templates.
}
// variable holds the dynamic value of a variable such as $, $x etc.
@ -221,17 +220,9 @@ func (t *Template) DefinedTemplates() string {
return s
}
type rangeControl int8
const (
rangeNone rangeControl = iota // no action.
rangeBreak // break out of range.
rangeContinue // continues next range iteration.
)
// Walk functions step through the major pieces of the template structure,
// generating output as they go.
func (s *state) walk(dot reflect.Value, node parse.Node) rangeControl {
func (s *state) walk(dot reflect.Value, node parse.Node) {
s.at(node)
switch node := node.(type) {
case *parse.ActionNode:
@ -242,15 +233,13 @@ func (s *state) walk(dot reflect.Value, node parse.Node) rangeControl {
s.printValue(node, val)
}
case *parse.IfNode:
return s.walkIfOrWith(parse.NodeIf, dot, node.Pipe, node.List, node.ElseList)
s.walkIfOrWith(parse.NodeIf, dot, node.Pipe, node.List, node.ElseList)
case *parse.ListNode:
for _, node := range node.Nodes {
if c := s.walk(dot, node); c != rangeNone {
return c
}
s.walk(dot, node)
}
case *parse.RangeNode:
return s.walkRange(dot, node)
s.walkRange(dot, node)
case *parse.TemplateNode:
s.walkTemplate(dot, node)
case *parse.TextNode:
@ -258,26 +247,15 @@ func (s *state) walk(dot reflect.Value, node parse.Node) rangeControl {
s.writeError(err)
}
case *parse.WithNode:
return s.walkIfOrWith(parse.NodeWith, dot, node.Pipe, node.List, node.ElseList)
case *parse.BreakNode:
if s.rangeDepth == 0 {
s.errorf("invalid break outside of range")
}
return rangeBreak
case *parse.ContinueNode:
if s.rangeDepth == 0 {
s.errorf("invalid continue outside of range")
}
return rangeContinue
s.walkIfOrWith(parse.NodeWith, dot, node.Pipe, node.List, node.ElseList)
default:
s.errorf("unknown node: %s", node)
}
return rangeNone
}
// walkIfOrWith walks an 'if' or 'with' node. The two control structures
// are identical in behavior except that 'with' sets dot.
func (s *state) walkIfOrWith(typ parse.NodeType, dot reflect.Value, pipe *parse.PipeNode, list, elseList *parse.ListNode) rangeControl {
func (s *state) walkIfOrWith(typ parse.NodeType, dot reflect.Value, pipe *parse.PipeNode, list, elseList *parse.ListNode) {
defer s.pop(s.mark())
val := s.evalPipeline(dot, pipe)
truth, ok := isTrue(val)
@ -286,14 +264,13 @@ func (s *state) walkIfOrWith(typ parse.NodeType, dot reflect.Value, pipe *parse.
}
if truth {
if typ == parse.NodeWith {
return s.walk(val, list)
s.walk(val, list)
} else {
return s.walk(dot, list)
s.walk(dot, list)
}
} else if elseList != nil {
return s.walk(dot, elseList)
s.walk(dot, elseList)
}
return rangeNone
}
// IsTrue reports whether the value is 'true', in the sense of not the zero of its type,
@ -331,14 +308,13 @@ func isTrue(val reflect.Value) (truth, ok bool) {
return truth, true
}
func (s *state) walkRange(dot reflect.Value, r *parse.RangeNode) rangeControl {
func (s *state) walkRange(dot reflect.Value, r *parse.RangeNode) {
s.at(r)
defer s.pop(s.mark())
val, _ := indirect(s.evalPipeline(dot, r.Pipe))
// mark top of stack before any variables in the body are pushed.
mark := s.mark()
s.rangeDepth++
oneIteration := func(index, elem reflect.Value) rangeControl {
oneIteration := func(index, elem reflect.Value) {
// Set top var (lexically the second if there are two) to the element.
if len(r.Pipe.Decl) > 0 {
s.setVar(1, elem)
@ -347,9 +323,8 @@ func (s *state) walkRange(dot reflect.Value, r *parse.RangeNode) rangeControl {
if len(r.Pipe.Decl) > 1 {
s.setVar(2, index)
}
ctrl := s.walk(elem, r.List)
s.walk(elem, r.List)
s.pop(mark)
return ctrl
}
switch val.Kind() {
case reflect.Array, reflect.Slice:
@ -357,23 +332,17 @@ func (s *state) walkRange(dot reflect.Value, r *parse.RangeNode) rangeControl {
break
}
for i := 0; i < val.Len(); i++ {
if ctrl := oneIteration(reflect.ValueOf(i), val.Index(i)); ctrl == rangeBreak {
break
}
oneIteration(reflect.ValueOf(i), val.Index(i))
}
s.rangeDepth--
return rangeNone
return
case reflect.Map:
if val.Len() == 0 {
break
}
for _, key := range sortKeys(val.MapKeys()) {
if ctrl := oneIteration(key, val.MapIndex(key)); ctrl == rangeBreak {
break
}
oneIteration(key, val.MapIndex(key))
}
s.rangeDepth--
return rangeNone
return
case reflect.Chan:
if val.IsNil() {
break
@ -384,25 +353,20 @@ func (s *state) walkRange(dot reflect.Value, r *parse.RangeNode) rangeControl {
if !ok {
break
}
if ctrl := oneIteration(reflect.ValueOf(i), elem); ctrl == rangeBreak {
break
}
oneIteration(reflect.ValueOf(i), elem)
}
if i == 0 {
break
}
s.rangeDepth--
return rangeNone
return
case reflect.Invalid:
break // An invalid value is likely a nil map, etc. and acts like an empty map.
default:
s.errorf("range can't iterate over %v", val)
}
s.rangeDepth--
if r.ElseList != nil {
return s.walk(dot, r.ElseList)
s.walk(dot, r.ElseList)
}
return rangeNone
}
func (s *state) walkTemplate(dot reflect.Value, t *parse.TemplateNode) {

4
src/text/template/exec_test.go
View File

@ -513,10 +513,6 @@ var execTests = []execTest{
{"declare in range", "{{range $x := .PSI}}<{{$foo:=$x}}{{$x}}>{{end}}", "<21><22><23>", tVal, true},
{"range count", `{{range $i, $x := count 5}}[{{$i}}]{{$x}}{{end}}`, "[0]a[1]b[2]c[3]d[4]e", tVal, true},
{"range nil count", `{{range $i, $x := count 0}}{{else}}empty{{end}}`, "empty", tVal, true},
{"range quick break", `{{range .SI}}{{break}}{{.}}{{end}}`, "", tVal, true},
{"range break after two", `{{range $i, $x := .SI}}{{if ge $i 2}}{{break}}{{end}}{{.}}{{end}}`, "34", tVal, true},
{"range continue", `{{range .SI}}{{continue}}{{.}}{{end}}`, "", tVal, true},
{"range continue condition", `{{range .SI}}{{if eq . 3 }}{{continue}}{{end}}{{.}}{{end}}`, "45", tVal, true},
// Cute examples.
{"or as if true", `{{or .SI "slice is empty"}}`, "[3 4 5]", tVal, true},

4
src/text/template/parse/lex.go
View File

@ -60,8 +60,6 @@ const (
// Keywords appear after all the rest.
itemKeyword // used only to delimit the keywords
itemBlock // block keyword
itemBreak // break keyword
itemContinue // continue keyword
itemDot // the cursor, spelled '.'
itemDefine // define keyword
itemElse // else keyword
@ -76,8 +74,6 @@ const (
var key = map[string]itemType{
".": itemDot,
"block": itemBlock,
"break": itemBreak,
"continue": itemContinue,
"define": itemDefine,
"else": itemElse,
"end": itemEnd,

6
src/text/template/parse/lex_test.go
View File

@ -192,7 +192,7 @@ var lexTests = []lexTest{
tRight,
tEOF,
}},
{"keywords", "{{range if else end with break continue}}", []item{
{"keywords", "{{range if else end with}}", []item{
tLeft,
mkItem(itemRange, "range"),
tSpace,
@ -203,10 +203,6 @@ var lexTests = []lexTest{
mkItem(itemEnd, "end"),
tSpace,
mkItem(itemWith, "with"),
tSpace,
mkItem(itemBreak, "break"),
tSpace,
mkItem(itemContinue, "continue"),
tRight,
tEOF,
}},

64
src/text/template/parse/node.go
View File

@ -69,8 +69,6 @@ const (
NodeTemplate // A template invocation action.
NodeVariable // A $ variable.
NodeWith // A with action.
NodeBreak // A break action.
NodeContinue // A continue action.
)
// Nodes.
@ -798,68 +796,6 @@ func (r *RangeNode) Copy() Node {
return r.tr.newRange(r.Pos, r.Line, r.Pipe.CopyPipe(), r.List.CopyList(), r.ElseList.CopyList())
}
// BreakNode represents a {{break}} action.
type BreakNode struct {
NodeType
Pos
tr *Tree
}
func (t *Tree) newBreak(pos Pos) *BreakNode {
return &BreakNode{NodeType: NodeBreak, Pos: pos, tr: t}
}
func (b *BreakNode) Type() NodeType {
return b.NodeType
}
func (b *BreakNode) String() string {
return "{{break}}"
}
func (b *BreakNode) Copy() Node {
return b.tr.newBreak(b.Pos)
}
func (b *BreakNode) Position() Pos {
return b.Pos
}
func (b *BreakNode) tree() *Tree {
return b.tr
}
// ContinueNode represents a {{continue}} action.
type ContinueNode struct {
NodeType
Pos
tr *Tree
}
func (t *Tree) newContinue(pos Pos) *ContinueNode {
return &ContinueNode{NodeType: NodeContinue, Pos: pos, tr: t}
}
func (c *ContinueNode) Type() NodeType {
return c.NodeType
}
func (c *ContinueNode) String() string {
return "{{continue}}"
}
func (c *ContinueNode) Copy() Node {
return c.tr.newContinue(c.Pos)
}
func (c *ContinueNode) Position() Pos {
return c.Pos
}
func (c *ContinueNode) tree() *Tree {
return c.tr
}
// WithNode represents a {{with}} action and its commands.
type WithNode struct {
BranchNode

44
src/text/template/parse/parse.go
View File

@ -23,13 +23,12 @@ type Tree struct {
Root *ListNode // top-level root of the tree.
text string // text parsed to create the template (or its parent)
// Parsing only; cleared after parse.
funcs []map[string]interface{}
lex *lexer
token [3]item // three-token lookahead for parser.
peekCount int
vars []string // variables defined at the moment.
treeSet map[string]*Tree
rangeDepth int // nesting level of range loops.
funcs []map[string]interface{}
lex *lexer
token [3]item // three-token lookahead for parser.
peekCount int
vars []string // variables defined at the moment.
treeSet map[string]*Tree
}
// Copy returns a copy of the Tree. Any parsing state is discarded.
@ -220,7 +219,6 @@ func (t *Tree) stopParse() {
t.vars = nil
t.funcs = nil
t.treeSet = nil
t.rangeDepth = 0
}
// Parse parses the template definition string to construct a representation of
@ -375,10 +373,6 @@ func (t *Tree) action() (n Node) {
return t.templateControl()
case itemWith:
return t.withControl()
case itemBreak:
return t.breakControl()
case itemContinue:
return t.continueControl()
}
t.backup()
token := t.peek()
@ -459,13 +453,7 @@ func (t *Tree) parseControl(allowElseIf bool, context string) (pos Pos, line int
defer t.popVars(len(t.vars))
pipe = t.pipeline(context)
var next Node
if context == "range" {
t.rangeDepth++
}
list, next = t.itemList()
if context == "range" {
t.rangeDepth--
}
switch next.Type() {
case nodeEnd: //done
case nodeElse:
@ -510,26 +498,6 @@ func (t *Tree) rangeControl() Node {
return t.newRange(t.parseControl(false, "range"))
}
// Break:
// {{break}}
// Break keyword is past.
func (t *Tree) breakControl() Node {
if t.rangeDepth == 0 {
t.errorf("unexpected break outside of range")
}
return t.newBreak(t.expect(itemRightDelim, "break").pos)
}
// Continue:
// {{continue}}
// Continue keyword is past.
func (t *Tree) continueControl() Node {
if t.rangeDepth == 0 {
t.errorf("unexpected continue outside of range")
}
return t.newContinue(t.expect(itemRightDelim, "continue").pos)
}
// With:
// {{with pipeline}} itemList {{end}}
// {{with pipeline}} itemList {{else}} itemList {{end}}

12
src/text/template/parse/parse_test.go
View File

@ -218,12 +218,6 @@ var parseTests = []parseTest{
`{{range $x := .SI}}{{.}}{{end}}`},
{"range 2 vars", "{{range $x, $y := .SI}}{{.}}{{end}}", noError,
`{{range $x, $y := .SI}}{{.}}{{end}}`},
{"range []int with break", "{{range .SI}}{{break}}{{.}}{{end}}", noError,
`{{range .SI}}{{break}}{{.}}{{end}}`},
{"range []int with break in else", "{{range .SI}}{{range .SI}}{{.}}{{else}}{{break}}{{end}}{{end}}", noError,
`{{range .SI}}{{range .SI}}{{.}}{{else}}{{break}}{{end}}{{end}}`},
{"range []int with continue", "{{range .SI}}{{continue}}{{.}}{{end}}", noError,
`{{range .SI}}{{continue}}{{.}}{{end}}`},
{"constants", "{{range .SI 1 -3.2i true false 'a' nil}}{{end}}", noError,
`{{range .SI 1 -3.2i true false 'a' nil}}{{end}}`},
{"template", "{{template `x`}}", noError,
@ -294,12 +288,6 @@ var parseTests = []parseTest{
{"empty pipeline", `{{printf "%d" ( ) }}`, hasError, ""},
// Missing pipeline in block
{"block definition", `{{block "foo"}}hello{{end}}`, hasError, ""},
// Invalid range control
{"break outside of range", `{{break}}`, hasError, ""},
{"break in range else, outside of range", `{{range .}}{{.}}{{else}}{{break}}{{end}}`, hasError, ""},
{"continue outside of range", `{{continue}}`, hasError, ""},
{"continue in range else, outside of range", `{{range .}}{{.}}{{else}}{{continue}}{{end}}`, hasError, ""},
{"additional break data", `{{range .}}{{break label}}{{end}}`, hasError, ""},
}
var builtins = map[string]interface{}{