From 1e5c432e1029601a664454388ae366ef69618d62 Mon Sep 17 00:00:00 2001 From: Christopher Speller Date: Mon, 25 Jun 2018 12:33:13 -0700 Subject: MM-10702 Moving plugins to use hashicorp go-plugin. (#8978) * Moving plugins to use hashicorp go-plugin. * Tweaks from feedback. --- vendor/github.com/alecthomas/template/exec.go | 845 ++++++++++++++++++++++++++ 1 file changed, 845 insertions(+) create mode 100644 vendor/github.com/alecthomas/template/exec.go (limited to 'vendor/github.com/alecthomas/template/exec.go') diff --git a/vendor/github.com/alecthomas/template/exec.go b/vendor/github.com/alecthomas/template/exec.go new file mode 100644 index 000000000..c3078e5d0 --- /dev/null +++ b/vendor/github.com/alecthomas/template/exec.go @@ -0,0 +1,845 @@ +// Copyright 2011 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package template + +import ( + "bytes" + "fmt" + "io" + "reflect" + "runtime" + "sort" + "strings" + + "github.com/alecthomas/template/parse" +) + +// state represents the state of an execution. It's not part of the +// 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. +} + +// variable holds the dynamic value of a variable such as $, $x etc. +type variable struct { + name string + value reflect.Value +} + +// push pushes a new variable on the stack. +func (s *state) push(name string, value reflect.Value) { + s.vars = append(s.vars, variable{name, value}) +} + +// mark returns the length of the variable stack. +func (s *state) mark() int { + return len(s.vars) +} + +// pop pops the variable stack up to the mark. +func (s *state) pop(mark int) { + s.vars = s.vars[0:mark] +} + +// setVar overwrites the top-nth variable on the stack. Used by range iterations. +func (s *state) setVar(n int, value reflect.Value) { + s.vars[len(s.vars)-n].value = value +} + +// varValue returns the value of the named variable. +func (s *state) varValue(name string) reflect.Value { + for i := s.mark() - 1; i >= 0; i-- { + if s.vars[i].name == name { + return s.vars[i].value + } + } + s.errorf("undefined variable: %s", name) + return zero +} + +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{}) { + 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...)) +} + +// errRecover is the handler that turns panics into returns from the top +// level of Parse. +func errRecover(errp *error) { + e := recover() + if e != nil { + switch err := e.(type) { + case runtime.Error: + panic(e) + case error: + *errp = err + default: + panic(e) + } + } +} + +// ExecuteTemplate applies the template associated with t that has the given name +// to the specified data object and writes the output to wr. +// If an error occurs executing the template or writing its output, +// execution stops, but partial results may already have been written to +// the output writer. +// A template may be executed safely in parallel. +func (t *Template) ExecuteTemplate(wr io.Writer, name string, data interface{}) error { + tmpl := t.tmpl[name] + if tmpl == nil { + return fmt.Errorf("template: no template %q associated with template %q", name, t.name) + } + return tmpl.Execute(wr, data) +} + +// Execute applies a parsed template to the specified data object, +// and writes the output to wr. +// If an error occurs executing the template or writing its output, +// execution stops, but partial results may already have been written to +// the output writer. +// A template may be executed safely in parallel. +func (t *Template) Execute(wr io.Writer, data interface{}) (err error) { + defer errRecover(&err) + value := reflect.ValueOf(data) + state := &state{ + tmpl: t, + wr: wr, + vars: []variable{{"$", value}}, + } + t.init() + if t.Tree == nil || t.Root == nil { + var b bytes.Buffer + for name, tmpl := range t.tmpl { + if tmpl.Tree == nil || tmpl.Root == nil { + continue + } + if b.Len() > 0 { + b.WriteString(", ") + } + fmt.Fprintf(&b, "%q", name) + } + var s string + if b.Len() > 0 { + s = "; defined templates are: " + b.String() + } + state.errorf("%q is an incomplete or empty template%s", t.Name(), s) + } + state.walk(value, t.Root) + return +} + +// 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) { + s.at(node) + switch node := node.(type) { + case *parse.ActionNode: + // 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, node.Pipe) + if len(node.Pipe.Decl) == 0 { + s.printValue(node, val) + } + case *parse.IfNode: + s.walkIfOrWith(parse.NodeIf, dot, node.Pipe, node.List, node.ElseList) + case *parse.ListNode: + for _, node := range node.Nodes { + s.walk(dot, node) + } + case *parse.RangeNode: + s.walkRange(dot, node) + case *parse.TemplateNode: + s.walkTemplate(dot, node) + case *parse.TextNode: + if _, err := s.wr.Write(node.Text); err != nil { + s.errorf("%s", err) + } + case *parse.WithNode: + s.walkIfOrWith(parse.NodeWith, dot, node.Pipe, node.List, node.ElseList) + default: + s.errorf("unknown node: %s", node) + } +} + +// 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) { + defer s.pop(s.mark()) + val := s.evalPipeline(dot, pipe) + truth, ok := isTrue(val) + if !ok { + s.errorf("if/with can't use %v", val) + } + if truth { + if typ == parse.NodeWith { + s.walk(val, list) + } else { + s.walk(dot, list) + } + } else if elseList != nil { + s.walk(dot, elseList) + } +} + +// isTrue reports whether the value is 'true', in the sense of not the zero of its type, +// and whether the value has a meaningful truth value. +func isTrue(val reflect.Value) (truth, ok bool) { + if !val.IsValid() { + // Something like var x interface{}, never set. It's a form of nil. + return false, true + } + switch val.Kind() { + case reflect.Array, reflect.Map, reflect.Slice, reflect.String: + truth = val.Len() > 0 + case reflect.Bool: + truth = val.Bool() + case reflect.Complex64, reflect.Complex128: + truth = val.Complex() != 0 + case reflect.Chan, reflect.Func, reflect.Ptr, reflect.Interface: + truth = !val.IsNil() + case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64: + truth = val.Int() != 0 + case reflect.Float32, reflect.Float64: + truth = val.Float() != 0 + case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr: + truth = val.Uint() != 0 + case reflect.Struct: + truth = true // Struct values are always true. + default: + return + } + return truth, true +} + +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() + 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) + } + // Set next var (lexically the first if there are two) to the index. + if len(r.Pipe.Decl) > 1 { + s.setVar(2, index) + } + s.walk(elem, r.List) + s.pop(mark) + } + switch val.Kind() { + case reflect.Array, reflect.Slice: + if val.Len() == 0 { + break + } + for i := 0; i < val.Len(); i++ { + oneIteration(reflect.ValueOf(i), val.Index(i)) + } + return + case reflect.Map: + if val.Len() == 0 { + break + } + for _, key := range sortKeys(val.MapKeys()) { + oneIteration(key, val.MapIndex(key)) + } + return + case reflect.Chan: + if val.IsNil() { + break + } + i := 0 + for ; ; i++ { + elem, ok := val.Recv() + if !ok { + break + } + oneIteration(reflect.ValueOf(i), elem) + } + if i == 0 { + break + } + 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) + } + if r.ElseList != nil { + s.walk(dot, r.ElseList) + } +} + +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) + } + // Variables declared by the pipeline persist. + dot = s.evalPipeline(dot, t.Pipe) + newState := *s + newState.tmpl = tmpl + // No dynamic scoping: template invocations inherit no variables. + newState.vars = []variable{{"$", dot}} + newState.walk(dot, tmpl.Root) +} + +// Eval functions evaluate pipelines, commands, and their elements and extract +// values from the data structure by examining fields, calling methods, and so on. +// The printing of those values happens only through walk functions. + +// evalPipeline returns the value acquired by evaluating a pipeline. If the +// pipeline has a variable declaration, the variable will be pushed on the +// stack. Callers should therefore pop the stack after they are finished +// executing commands depending on the pipeline value. +func (s *state) evalPipeline(dot reflect.Value, pipe *parse.PipeNode) (value reflect.Value) { + 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. + if value.Kind() == reflect.Interface && value.Type().NumMethod() == 0 { + value = reflect.ValueOf(value.Interface()) // lovely! + } + } + for _, variable := range pipe.Decl { + s.push(variable.Ident[0], value) + } + return value +} + +func (s *state) notAFunction(args []parse.Node, final reflect.Value) { + if len(args) > 1 || final.IsValid() { + s.errorf("can't give argument to non-function %s", args[0]) + } +} + +func (s *state) evalCommand(dot reflect.Value, cmd *parse.CommandNode, final reflect.Value) reflect.Value { + firstWord := cmd.Args[0] + 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, 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: + return reflect.ValueOf(word.Text) + } + s.errorf("can't evaluate command %q", firstWord) + panic("not reached") +} + +// idealConstant is called to return the value of a number in a context where +// we don't know the type. In that case, the syntax of the number tells us +// its type, and we use Go rules to resolve. Note there is no such thing as +// a uint ideal constant in this situation - the value must be of int type. +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. + case constant.IsFloat && !isHexConstant(constant.Text) && strings.IndexAny(constant.Text, ".eE") >= 0: + return reflect.ValueOf(constant.Float64) + case constant.IsInt: + n := int(constant.Int64) + if int64(n) != constant.Int64 { + s.errorf("%s overflows int", constant.Text) + } + return reflect.ValueOf(n) + case constant.IsUint: + s.errorf("%s overflows int", constant.Text) + } + return zero +} + +func isHexConstant(s string) bool { + return len(s) > 2 && s[0] == '0' && (s[1] == 'x' || s[1] == 'X') +} + +func (s *state) evalFieldNode(dot reflect.Value, field *parse.FieldNode, args []parse.Node, final reflect.Value) reflect.Value { + 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, 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. + 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, 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, 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], node, nil, zero, receiver) + } + // Now if it's a method, it gets the arguments. + return s.evalField(dot, ident[n-1], node, args, final, receiver) +} + +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, 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, node parse.Node, args []parse.Node, final, receiver reflect.Value) reflect.Value { + if !receiver.IsValid() { + return zero + } + typ := receiver.Type() + receiver, _ = indirect(receiver) + // Unless it's an interface, need to get to a value of type *T to guarantee + // we see all methods of T and *T. + ptr := receiver + if ptr.Kind() != reflect.Interface && ptr.CanAddr() { + ptr = ptr.Addr() + } + if method := ptr.MethodByName(fieldName); method.IsValid() { + return s.evalCall(dot, method, node, fieldName, args, final) + } + hasArgs := len(args) > 1 || final.IsValid() + // 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 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 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 + } + 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 { + s.errorf("%s is not a method but has arguments", fieldName) + } + return receiver.MapIndex(nameVal) + } + } + s.errorf("can't evaluate field %s in type %s", fieldName, typ) + panic("not reached") +} + +var ( + errorType = reflect.TypeOf((*error)(nil)).Elem() + fmtStringerType = reflect.TypeOf((*fmt.Stringer)(nil)).Elem() +) + +// 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, 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. + } + typ := fun.Type() + numIn := len(args) + if final.IsValid() { + numIn++ + } + numFixed := len(args) + if typ.IsVariadic() { + numFixed = typ.NumIn() - 1 // last arg is the variadic one. + if numIn < numFixed { + s.errorf("wrong number of args for %s: want at least %d got %d", name, typ.NumIn()-1, len(args)) + } + } else if numIn < typ.NumIn()-1 || !typ.IsVariadic() && numIn != typ.NumIn() { + s.errorf("wrong number of args for %s: want %d got %d", name, typ.NumIn(), len(args)) + } + if !goodFunc(typ) { + // 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) + // Args must be evaluated. Fixed args first. + i := 0 + for ; i < numFixed && i < len(args); i++ { + argv[i] = s.evalArg(dot, typ.In(i), args[i]) + } + // Now the ... args. + if typ.IsVariadic() { + argType := typ.In(typ.NumIn() - 1).Elem() // Argument is a slice. + for ; i < len(args); i++ { + argv[i] = s.evalArg(dot, argType, args[i]) + } + } + // Add final value if necessary. + if final.IsValid() { + t := typ.In(typ.NumIn() - 1) + if typ.IsVariadic() { + t = t.Elem() + } + argv[i] = s.validateType(final, t) + } + 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() { + if typ == nil || canBeNil(typ) { + // An untyped nil interface{}. Accept as a proper nil value. + return reflect.Zero(typ) + } + s.errorf("invalid value; expected %s", typ) + } + if typ != nil && !value.Type().AssignableTo(typ) { + if value.Kind() == reflect.Interface && !value.IsNil() { + value = value.Elem() + if value.Type().AssignableTo(typ) { + return value + } + // fallthrough + } + // Does one dereference or indirection work? We could do more, as we + // do with method receivers, but that gets messy and method receivers + // are much more constrained, so it makes more sense there than here. + // Besides, one is almost always all you need. + switch { + case value.Kind() == reflect.Ptr && value.Type().Elem().AssignableTo(typ): + value = value.Elem() + if !value.IsValid() { + s.errorf("dereference of nil pointer of type %s", typ) + } + case reflect.PtrTo(value.Type()).AssignableTo(typ) && value.CanAddr(): + value = value.Addr() + default: + s.errorf("wrong type for value; expected %s; got %s", typ, value.Type()) + } + } + return value +} + +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) + case *parse.IdentifierNode: + return s.evalFunction(dot, arg, arg, nil, zero) + case *parse.ChainNode: + return s.validateType(s.evalChainNode(dot, arg, nil, zero), typ) + } + switch typ.Kind() { + case reflect.Bool: + return s.evalBool(typ, n) + case reflect.Complex64, reflect.Complex128: + return s.evalComplex(typ, n) + case reflect.Float32, reflect.Float64: + return s.evalFloat(typ, n) + case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64: + return s.evalInteger(typ, n) + case reflect.Interface: + if typ.NumMethod() == 0 { + return s.evalEmptyInterface(dot, n) + } + case reflect.String: + return s.evalString(typ, n) + case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr: + return s.evalUnsignedInteger(typ, n) + } + s.errorf("can't handle %s for arg of type %s", n, typ) + panic("not reached") +} + +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) + return value + } + s.errorf("expected bool; found %s", n) + panic("not reached") +} + +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) + return value + } + s.errorf("expected string; found %s", n) + panic("not reached") +} + +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) + return value + } + s.errorf("expected integer; found %s", n) + panic("not reached") +} + +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) + return value + } + s.errorf("expected unsigned integer; found %s", n) + panic("not reached") +} + +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) + return value + } + s.errorf("expected float; found %s", n) + panic("not reached") +} + +func (s *state) evalComplex(typ reflect.Type, n parse.Node) reflect.Value { + if n, ok := n.(*parse.NumberNode); ok && n.IsComplex { + value := reflect.New(typ).Elem() + value.SetComplex(n.Complex128) + return value + } + s.errorf("expected complex; found %s", n) + panic("not reached") +} + +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) + case *parse.DotNode: + return dot + case *parse.FieldNode: + return s.evalFieldNode(dot, n, nil, zero) + case *parse.IdentifierNode: + 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") +} + +// indirect returns the item at the end of indirection, and a bool to indicate if it's nil. +// We indirect through pointers and empty interfaces (only) because +// non-empty interfaces have methods we might need. +func indirect(v reflect.Value) (rv reflect.Value, isNil bool) { + for ; v.Kind() == reflect.Ptr || v.Kind() == reflect.Interface; v = v.Elem() { + if v.IsNil() { + return v, true + } + if v.Kind() == reflect.Interface && v.NumMethod() > 0 { + break + } + } + return v, false +} + +// 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) + iface, ok := printableValue(v) + if !ok { + s.errorf("can't print %s of type %s", n, v.Type()) + } + fmt.Fprint(s.wr, iface) +} + +// printableValue returns the, possibly indirected, interface value inside v that +// is best for a call to formatted printer. +func printableValue(v reflect.Value) (interface{}, bool) { + if v.Kind() == reflect.Ptr { + v, _ = indirect(v) // fmt.Fprint handles nil. + } + if !v.IsValid() { + return "", true + } + + if !v.Type().Implements(errorType) && !v.Type().Implements(fmtStringerType) { + if v.CanAddr() && (reflect.PtrTo(v.Type()).Implements(errorType) || reflect.PtrTo(v.Type()).Implements(fmtStringerType)) { + v = v.Addr() + } else { + switch v.Kind() { + case reflect.Chan, reflect.Func: + return nil, false + } + } + } + return v.Interface(), true +} + +// Types to help sort the keys in a map for reproducible output. + +type rvs []reflect.Value + +func (x rvs) Len() int { return len(x) } +func (x rvs) Swap(i, j int) { x[i], x[j] = x[j], x[i] } + +type rvInts struct{ rvs } + +func (x rvInts) Less(i, j int) bool { return x.rvs[i].Int() < x.rvs[j].Int() } + +type rvUints struct{ rvs } + +func (x rvUints) Less(i, j int) bool { return x.rvs[i].Uint() < x.rvs[j].Uint() } + +type rvFloats struct{ rvs } + +func (x rvFloats) Less(i, j int) bool { return x.rvs[i].Float() < x.rvs[j].Float() } + +type rvStrings struct{ rvs } + +func (x rvStrings) Less(i, j int) bool { return x.rvs[i].String() < x.rvs[j].String() } + +// sortKeys sorts (if it can) the slice of reflect.Values, which is a slice of map keys. +func sortKeys(v []reflect.Value) []reflect.Value { + if len(v) <= 1 { + return v + } + switch v[0].Kind() { + case reflect.Float32, reflect.Float64: + sort.Sort(rvFloats{v}) + case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64: + sort.Sort(rvInts{v}) + case reflect.String: + sort.Sort(rvStrings{v}) + case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr: + sort.Sort(rvUints{v}) + } + return v +} -- cgit v1.2.3-1-g7c22