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Diffstat (limited to 'src/pkg/text/template/exec.go')
-rw-r--r--src/pkg/text/template/exec.go192
1 files changed, 129 insertions, 63 deletions
diff --git a/src/pkg/text/template/exec.go b/src/pkg/text/template/exec.go
index aba21ce28..b9c03d8f0 100644
--- a/src/pkg/text/template/exec.go
+++ b/src/pkg/text/template/exec.go
@@ -20,7 +20,7 @@ import (
type state struct {
tmpl *Template
wr io.Writer
- line int // line number for errors
+ node parse.Node // current node, for errors
vars []variable // push-down stack of variable values.
}
@@ -63,17 +63,32 @@ func (s *state) varValue(name string) reflect.Value {
var zero reflect.Value
+// at marks the state to be on node n, for error reporting.
+func (s *state) at(node parse.Node) {
+ s.node = node
+}
+
+// doublePercent returns the string with %'s replaced by %%, if necessary,
+// so it can be used safely inside a Printf format string.
+func doublePercent(str string) string {
+ if strings.Contains(str, "%") {
+ str = strings.Replace(str, "%", "%%", -1)
+ }
+ return str
+}
+
// errorf formats the error and terminates processing.
func (s *state) errorf(format string, args ...interface{}) {
- format = fmt.Sprintf("template: %s:%d: %s", s.tmpl.Name(), s.line, format)
+ name := doublePercent(s.tmpl.Name())
+ if s.node == nil {
+ format = fmt.Sprintf("template: %s: %s", name, format)
+ } else {
+ location, context := s.tmpl.ErrorContext(s.node)
+ format = fmt.Sprintf("template: %s: executing %q at <%s>: %s", location, name, doublePercent(context), format)
+ }
panic(fmt.Errorf(format, args...))
}
-// error terminates processing.
-func (s *state) error(err error) {
- s.errorf("%s", err)
-}
-
// errRecover is the handler that turns panics into returns from the top
// level of Parse.
func errRecover(errp *error) {
@@ -108,7 +123,6 @@ func (t *Template) Execute(wr io.Writer, data interface{}) (err error) {
state := &state{
tmpl: t,
wr: wr,
- line: 1,
vars: []variable{{"$", value}},
}
if t.Tree == nil || t.Root == nil {
@@ -120,38 +134,34 @@ func (t *Template) Execute(wr io.Writer, data interface{}) (err error) {
// Walk functions step through the major pieces of the template structure,
// generating output as they go.
-func (s *state) walk(dot reflect.Value, n parse.Node) {
- switch n := n.(type) {
+func (s *state) walk(dot reflect.Value, node parse.Node) {
+ s.at(node)
+ switch node := node.(type) {
case *parse.ActionNode:
- s.line = n.Line
// Do not pop variables so they persist until next end.
// Also, if the action declares variables, don't print the result.
- val := s.evalPipeline(dot, n.Pipe)
- if len(n.Pipe.Decl) == 0 {
- s.printValue(n, val)
+ val := s.evalPipeline(dot, node.Pipe)
+ if len(node.Pipe.Decl) == 0 {
+ s.printValue(node, val)
}
case *parse.IfNode:
- s.line = n.Line
- s.walkIfOrWith(parse.NodeIf, dot, n.Pipe, n.List, n.ElseList)
+ s.walkIfOrWith(parse.NodeIf, dot, node.Pipe, node.List, node.ElseList)
case *parse.ListNode:
- for _, node := range n.Nodes {
+ for _, node := range node.Nodes {
s.walk(dot, node)
}
case *parse.RangeNode:
- s.line = n.Line
- s.walkRange(dot, n)
+ s.walkRange(dot, node)
case *parse.TemplateNode:
- s.line = n.Line
- s.walkTemplate(dot, n)
+ s.walkTemplate(dot, node)
case *parse.TextNode:
- if _, err := s.wr.Write(n.Text); err != nil {
- s.error(err)
+ if _, err := s.wr.Write(node.Text); err != nil {
+ s.errorf("%s", err)
}
case *parse.WithNode:
- s.line = n.Line
- s.walkIfOrWith(parse.NodeWith, dot, n.Pipe, n.List, n.ElseList)
+ s.walkIfOrWith(parse.NodeWith, dot, node.Pipe, node.List, node.ElseList)
default:
- s.errorf("unknown node: %s", n)
+ s.errorf("unknown node: %s", node)
}
}
@@ -206,6 +216,7 @@ func isTrue(val reflect.Value) (truth, ok bool) {
}
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.
@@ -266,6 +277,7 @@ func (s *state) walkRange(dot reflect.Value, r *parse.RangeNode) {
}
func (s *state) walkTemplate(dot reflect.Value, t *parse.TemplateNode) {
+ s.at(t)
tmpl := s.tmpl.tmpl[t.Name]
if tmpl == nil {
s.errorf("template %q not defined", t.Name)
@@ -291,6 +303,7 @@ func (s *state) evalPipeline(dot reflect.Value, pipe *parse.PipeNode) (value ref
if pipe == nil {
return
}
+ s.at(pipe)
for _, cmd := range pipe.Cmds {
value = s.evalCommand(dot, cmd, value) // previous value is this one's final arg.
// If the object has type interface{}, dig down one level to the thing inside.
@@ -315,18 +328,26 @@ func (s *state) evalCommand(dot reflect.Value, cmd *parse.CommandNode, final ref
switch n := firstWord.(type) {
case *parse.FieldNode:
return s.evalFieldNode(dot, n, cmd.Args, final)
+ case *parse.ChainNode:
+ return s.evalChainNode(dot, n, cmd.Args, final)
case *parse.IdentifierNode:
// Must be a function.
- return s.evalFunction(dot, n.Ident, cmd.Args, final)
+ return s.evalFunction(dot, n, cmd, cmd.Args, final)
+ case *parse.PipeNode:
+ // Parenthesized pipeline. The arguments are all inside the pipeline; final is ignored.
+ return s.evalPipeline(dot, n)
case *parse.VariableNode:
return s.evalVariableNode(dot, n, cmd.Args, final)
}
+ s.at(firstWord)
s.notAFunction(cmd.Args, final)
switch word := firstWord.(type) {
case *parse.BoolNode:
return reflect.ValueOf(word.True)
case *parse.DotNode:
return dot
+ case *parse.NilNode:
+ s.errorf("nil is not a command")
case *parse.NumberNode:
return s.idealConstant(word)
case *parse.StringNode:
@@ -344,6 +365,7 @@ func (s *state) idealConstant(constant *parse.NumberNode) reflect.Value {
// These are ideal constants but we don't know the type
// and we have no context. (If it was a method argument,
// we'd know what we need.) The syntax guides us to some extent.
+ s.at(constant)
switch {
case constant.IsComplex:
return reflect.ValueOf(constant.Complex128) // incontrovertible.
@@ -362,43 +384,57 @@ func (s *state) idealConstant(constant *parse.NumberNode) reflect.Value {
}
func (s *state) evalFieldNode(dot reflect.Value, field *parse.FieldNode, args []parse.Node, final reflect.Value) reflect.Value {
- return s.evalFieldChain(dot, dot, field.Ident, args, final)
+ s.at(field)
+ return s.evalFieldChain(dot, dot, field, field.Ident, args, final)
+}
+
+func (s *state) evalChainNode(dot reflect.Value, chain *parse.ChainNode, args []parse.Node, final reflect.Value) reflect.Value {
+ s.at(chain)
+ // (pipe).Field1.Field2 has pipe as .Node, fields as .Field. Eval the pipeline, then the fields.
+ pipe := s.evalArg(dot, nil, chain.Node)
+ if len(chain.Field) == 0 {
+ s.errorf("internal error: no fields in evalChainNode")
+ }
+ return s.evalFieldChain(dot, pipe, chain, chain.Field, args, final)
}
-func (s *state) evalVariableNode(dot reflect.Value, v *parse.VariableNode, args []parse.Node, final reflect.Value) reflect.Value {
+func (s *state) evalVariableNode(dot reflect.Value, variable *parse.VariableNode, args []parse.Node, final reflect.Value) reflect.Value {
// $x.Field has $x as the first ident, Field as the second. Eval the var, then the fields.
- value := s.varValue(v.Ident[0])
- if len(v.Ident) == 1 {
+ s.at(variable)
+ value := s.varValue(variable.Ident[0])
+ if len(variable.Ident) == 1 {
s.notAFunction(args, final)
return value
}
- return s.evalFieldChain(dot, value, v.Ident[1:], args, final)
+ return s.evalFieldChain(dot, value, variable, variable.Ident[1:], args, final)
}
// evalFieldChain evaluates .X.Y.Z possibly followed by arguments.
// dot is the environment in which to evaluate arguments, while
// receiver is the value being walked along the chain.
-func (s *state) evalFieldChain(dot, receiver reflect.Value, ident []string, args []parse.Node, final reflect.Value) reflect.Value {
+func (s *state) evalFieldChain(dot, receiver reflect.Value, node parse.Node, ident []string, args []parse.Node, final reflect.Value) reflect.Value {
n := len(ident)
for i := 0; i < n-1; i++ {
- receiver = s.evalField(dot, ident[i], nil, zero, receiver)
+ receiver = s.evalField(dot, ident[i], node, nil, zero, receiver)
}
// Now if it's a method, it gets the arguments.
- return s.evalField(dot, ident[n-1], args, final, receiver)
+ return s.evalField(dot, ident[n-1], node, args, final, receiver)
}
-func (s *state) evalFunction(dot reflect.Value, name string, args []parse.Node, final reflect.Value) reflect.Value {
+func (s *state) evalFunction(dot reflect.Value, node *parse.IdentifierNode, cmd parse.Node, args []parse.Node, final reflect.Value) reflect.Value {
+ s.at(node)
+ name := node.Ident
function, ok := findFunction(name, s.tmpl)
if !ok {
s.errorf("%q is not a defined function", name)
}
- return s.evalCall(dot, function, name, args, final)
+ return s.evalCall(dot, function, cmd, name, args, final)
}
// evalField evaluates an expression like (.Field) or (.Field arg1 arg2).
// The 'final' argument represents the return value from the preceding
// value of the pipeline, if any.
-func (s *state) evalField(dot reflect.Value, fieldName string, args []parse.Node, final, receiver reflect.Value) reflect.Value {
+func (s *state) evalField(dot reflect.Value, fieldName string, node parse.Node, args []parse.Node, final, receiver reflect.Value) reflect.Value {
if !receiver.IsValid() {
return zero
}
@@ -411,26 +447,31 @@ func (s *state) evalField(dot reflect.Value, fieldName string, args []parse.Node
ptr = ptr.Addr()
}
if method := ptr.MethodByName(fieldName); method.IsValid() {
- return s.evalCall(dot, method, fieldName, args, final)
+ return s.evalCall(dot, method, node, fieldName, args, final)
}
hasArgs := len(args) > 1 || final.IsValid()
- // It's not a method; is it a field of a struct?
+ // It's not a method; must be a field of a struct or an element of a map. The receiver must not be nil.
receiver, isNil := indirect(receiver)
- if receiver.Kind() == reflect.Struct {
+ if isNil {
+ s.errorf("nil pointer evaluating %s.%s", typ, fieldName)
+ }
+ switch receiver.Kind() {
+ case reflect.Struct:
tField, ok := receiver.Type().FieldByName(fieldName)
if ok {
field := receiver.FieldByIndex(tField.Index)
- if tField.PkgPath == "" { // field is exported
- // If it's a function, we must call it.
- if hasArgs {
- s.errorf("%s has arguments but cannot be invoked as function", fieldName)
- }
- return field
+ if tField.PkgPath != "" { // field is unexported
+ s.errorf("%s is an unexported field of struct type %s", fieldName, typ)
+ }
+ // If it's a function, we must call it.
+ if hasArgs {
+ s.errorf("%s has arguments but cannot be invoked as function", fieldName)
}
+ return field
}
- }
- // If it's a map, attempt to use the field name as a key.
- if receiver.Kind() == reflect.Map {
+ s.errorf("%s is not a field of struct type %s", fieldName, typ)
+ case reflect.Map:
+ // If it's a map, attempt to use the field name as a key.
nameVal := reflect.ValueOf(fieldName)
if nameVal.Type().AssignableTo(receiver.Type().Key()) {
if hasArgs {
@@ -439,9 +480,6 @@ func (s *state) evalField(dot reflect.Value, fieldName string, args []parse.Node
return receiver.MapIndex(nameVal)
}
}
- if isNil {
- s.errorf("nil pointer evaluating %s.%s", typ, fieldName)
- }
s.errorf("can't evaluate field %s in type %s", fieldName, typ)
panic("not reached")
}
@@ -454,7 +492,7 @@ var (
// evalCall executes a function or method call. If it's a method, fun already has the receiver bound, so
// it looks just like a function call. The arg list, if non-nil, includes (in the manner of the shell), arg[0]
// as the function itself.
-func (s *state) evalCall(dot, fun reflect.Value, name string, args []parse.Node, final reflect.Value) reflect.Value {
+func (s *state) evalCall(dot, fun reflect.Value, node parse.Node, name string, args []parse.Node, final reflect.Value) reflect.Value {
if args != nil {
args = args[1:] // Zeroth arg is function name/node; not passed to function.
}
@@ -473,7 +511,8 @@ func (s *state) evalCall(dot, fun reflect.Value, name string, args []parse.Node,
s.errorf("wrong number of args for %s: want %d got %d", name, typ.NumIn(), len(args))
}
if !goodFunc(typ) {
- s.errorf("can't handle multiple results from method/function %q", name)
+ // TODO: This could still be a confusing error; maybe goodFunc should provide info.
+ s.errorf("can't call method/function %q with %d results", name, typ.NumOut())
}
// Build the arg list.
argv := make([]reflect.Value, numIn)
@@ -500,24 +539,31 @@ func (s *state) evalCall(dot, fun reflect.Value, name string, args []parse.Node,
result := fun.Call(argv)
// If we have an error that is not nil, stop execution and return that error to the caller.
if len(result) == 2 && !result[1].IsNil() {
+ s.at(node)
s.errorf("error calling %s: %s", name, result[1].Interface().(error))
}
return result[0]
}
+// canBeNil reports whether an untyped nil can be assigned to the type. See reflect.Zero.
+func canBeNil(typ reflect.Type) bool {
+ switch typ.Kind() {
+ case reflect.Chan, reflect.Func, reflect.Interface, reflect.Map, reflect.Ptr, reflect.Slice:
+ return true
+ }
+ return false
+}
+
// validateType guarantees that the value is valid and assignable to the type.
func (s *state) validateType(value reflect.Value, typ reflect.Type) reflect.Value {
if !value.IsValid() {
- switch typ.Kind() {
- case reflect.Interface, reflect.Ptr, reflect.Chan, reflect.Map, reflect.Slice, reflect.Func:
+ if typ == nil || canBeNil(typ) {
// An untyped nil interface{}. Accept as a proper nil value.
- // TODO: Can we delete the other types in this list? Should we?
- value = reflect.Zero(typ)
- default:
- s.errorf("invalid value; expected %s", typ)
+ return reflect.Zero(typ)
}
+ s.errorf("invalid value; expected %s", typ)
}
- if !value.Type().AssignableTo(typ) {
+ if typ != nil && !value.Type().AssignableTo(typ) {
if value.Kind() == reflect.Interface && !value.IsNil() {
value = value.Elem()
if value.Type().AssignableTo(typ) {
@@ -542,13 +588,21 @@ func (s *state) validateType(value reflect.Value, typ reflect.Type) reflect.Valu
}
func (s *state) evalArg(dot reflect.Value, typ reflect.Type, n parse.Node) reflect.Value {
+ s.at(n)
switch arg := n.(type) {
case *parse.DotNode:
return s.validateType(dot, typ)
+ case *parse.NilNode:
+ if canBeNil(typ) {
+ return reflect.Zero(typ)
+ }
+ s.errorf("cannot assign nil to %s", typ)
case *parse.FieldNode:
return s.validateType(s.evalFieldNode(dot, arg, []parse.Node{n}, zero), typ)
case *parse.VariableNode:
return s.validateType(s.evalVariableNode(dot, arg, nil, zero), typ)
+ case *parse.PipeNode:
+ return s.validateType(s.evalPipeline(dot, arg), typ)
}
switch typ.Kind() {
case reflect.Bool:
@@ -573,6 +627,7 @@ func (s *state) evalArg(dot reflect.Value, typ reflect.Type, n parse.Node) refle
}
func (s *state) evalBool(typ reflect.Type, n parse.Node) reflect.Value {
+ s.at(n)
if n, ok := n.(*parse.BoolNode); ok {
value := reflect.New(typ).Elem()
value.SetBool(n.True)
@@ -583,6 +638,7 @@ func (s *state) evalBool(typ reflect.Type, n parse.Node) reflect.Value {
}
func (s *state) evalString(typ reflect.Type, n parse.Node) reflect.Value {
+ s.at(n)
if n, ok := n.(*parse.StringNode); ok {
value := reflect.New(typ).Elem()
value.SetString(n.Text)
@@ -593,6 +649,7 @@ func (s *state) evalString(typ reflect.Type, n parse.Node) reflect.Value {
}
func (s *state) evalInteger(typ reflect.Type, n parse.Node) reflect.Value {
+ s.at(n)
if n, ok := n.(*parse.NumberNode); ok && n.IsInt {
value := reflect.New(typ).Elem()
value.SetInt(n.Int64)
@@ -603,6 +660,7 @@ func (s *state) evalInteger(typ reflect.Type, n parse.Node) reflect.Value {
}
func (s *state) evalUnsignedInteger(typ reflect.Type, n parse.Node) reflect.Value {
+ s.at(n)
if n, ok := n.(*parse.NumberNode); ok && n.IsUint {
value := reflect.New(typ).Elem()
value.SetUint(n.Uint64)
@@ -613,6 +671,7 @@ func (s *state) evalUnsignedInteger(typ reflect.Type, n parse.Node) reflect.Valu
}
func (s *state) evalFloat(typ reflect.Type, n parse.Node) reflect.Value {
+ s.at(n)
if n, ok := n.(*parse.NumberNode); ok && n.IsFloat {
value := reflect.New(typ).Elem()
value.SetFloat(n.Float64)
@@ -633,6 +692,7 @@ func (s *state) evalComplex(typ reflect.Type, n parse.Node) reflect.Value {
}
func (s *state) evalEmptyInterface(dot reflect.Value, n parse.Node) reflect.Value {
+ s.at(n)
switch n := n.(type) {
case *parse.BoolNode:
return reflect.ValueOf(n.True)
@@ -641,13 +701,18 @@ func (s *state) evalEmptyInterface(dot reflect.Value, n parse.Node) reflect.Valu
case *parse.FieldNode:
return s.evalFieldNode(dot, n, nil, zero)
case *parse.IdentifierNode:
- return s.evalFunction(dot, n.Ident, nil, zero)
+ return s.evalFunction(dot, n, n, nil, zero)
+ case *parse.NilNode:
+ // NilNode is handled in evalArg, the only place that calls here.
+ s.errorf("evalEmptyInterface: nil (can't happen)")
case *parse.NumberNode:
return s.idealConstant(n)
case *parse.StringNode:
return reflect.ValueOf(n.Text)
case *parse.VariableNode:
return s.evalVariableNode(dot, n, nil, zero)
+ case *parse.PipeNode:
+ return s.evalPipeline(dot, n)
}
s.errorf("can't handle assignment of %s to empty interface argument", n)
panic("not reached")
@@ -671,6 +736,7 @@ func indirect(v reflect.Value) (rv reflect.Value, isNil bool) {
// printValue writes the textual representation of the value to the output of
// the template.
func (s *state) printValue(n parse.Node, v reflect.Value) {
+ s.at(n)
if v.Kind() == reflect.Ptr {
v, _ = indirect(v) // fmt.Fprint handles nil.
}
generated by cgit v1.2.3 (git 2.39.1) at 2024-07-09 23:17:32 +0000