From bae9f6d2fd5eb5bc80929bd393932b23f14d7c93 Mon Sep 17 00:00:00 2001 From: Jake Champlin Date: Tue, 6 Jun 2017 12:40:07 -0400 Subject: Initial transfer of provider code --- vendor/github.com/hashicorp/hil/eval.go | 472 ++++++++++++++++++++++++++++++++ 1 file changed, 472 insertions(+) create mode 100644 vendor/github.com/hashicorp/hil/eval.go (limited to 'vendor/github.com/hashicorp/hil/eval.go') diff --git a/vendor/github.com/hashicorp/hil/eval.go b/vendor/github.com/hashicorp/hil/eval.go new file mode 100644 index 0000000..2782076 --- /dev/null +++ b/vendor/github.com/hashicorp/hil/eval.go @@ -0,0 +1,472 @@ +package hil + +import ( + "bytes" + "errors" + "fmt" + "sync" + + "github.com/hashicorp/hil/ast" +) + +// EvalConfig is the configuration for evaluating. +type EvalConfig struct { + // GlobalScope is the global scope of execution for evaluation. + GlobalScope *ast.BasicScope + + // SemanticChecks is a list of additional semantic checks that will be run + // on the tree prior to evaluating it. The type checker, identifier checker, + // etc. will be run before these automatically. + SemanticChecks []SemanticChecker +} + +// SemanticChecker is the type that must be implemented to do a +// semantic check on an AST tree. This will be called with the root node. +type SemanticChecker func(ast.Node) error + +// EvaluationResult is a struct returned from the hil.Eval function, +// representing the result of an interpolation. Results are returned in their +// "natural" Go structure rather than in terms of the HIL AST. For the types +// currently implemented, this means that the Value field can be interpreted as +// the following Go types: +// TypeInvalid: undefined +// TypeString: string +// TypeList: []interface{} +// TypeMap: map[string]interface{} +// TypBool: bool +type EvaluationResult struct { + Type EvalType + Value interface{} +} + +// InvalidResult is a structure representing the result of a HIL interpolation +// which has invalid syntax, missing variables, or some other type of error. +// The error is described out of band in the accompanying error return value. +var InvalidResult = EvaluationResult{Type: TypeInvalid, Value: nil} + +// errExitUnknown is an internal error that when returned means the result +// is an unknown value. We use this for early exit. +var errExitUnknown = errors.New("unknown value") + +func Eval(root ast.Node, config *EvalConfig) (EvaluationResult, error) { + output, outputType, err := internalEval(root, config) + if err != nil { + return InvalidResult, err + } + + // If the result contains any nested unknowns then the result as a whole + // is unknown, so that callers only have to deal with "entirely known" + // or "entirely unknown" as outcomes. + if ast.IsUnknown(ast.Variable{Type: outputType, Value: output}) { + outputType = ast.TypeUnknown + output = UnknownValue + } + + switch outputType { + case ast.TypeList: + val, err := VariableToInterface(ast.Variable{ + Type: ast.TypeList, + Value: output, + }) + return EvaluationResult{ + Type: TypeList, + Value: val, + }, err + case ast.TypeMap: + val, err := VariableToInterface(ast.Variable{ + Type: ast.TypeMap, + Value: output, + }) + return EvaluationResult{ + Type: TypeMap, + Value: val, + }, err + case ast.TypeString: + return EvaluationResult{ + Type: TypeString, + Value: output, + }, nil + case ast.TypeBool: + return EvaluationResult{ + Type: TypeBool, + Value: output, + }, nil + case ast.TypeUnknown: + return EvaluationResult{ + Type: TypeUnknown, + Value: UnknownValue, + }, nil + default: + return InvalidResult, fmt.Errorf("unknown type %s as interpolation output", outputType) + } +} + +// Eval evaluates the given AST tree and returns its output value, the type +// of the output, and any error that occurred. +func internalEval(root ast.Node, config *EvalConfig) (interface{}, ast.Type, error) { + // Copy the scope so we can add our builtins + if config == nil { + config = new(EvalConfig) + } + scope := registerBuiltins(config.GlobalScope) + implicitMap := map[ast.Type]map[ast.Type]string{ + ast.TypeFloat: { + ast.TypeInt: "__builtin_FloatToInt", + ast.TypeString: "__builtin_FloatToString", + }, + ast.TypeInt: { + ast.TypeFloat: "__builtin_IntToFloat", + ast.TypeString: "__builtin_IntToString", + }, + ast.TypeString: { + ast.TypeInt: "__builtin_StringToInt", + ast.TypeFloat: "__builtin_StringToFloat", + ast.TypeBool: "__builtin_StringToBool", + }, + ast.TypeBool: { + ast.TypeString: "__builtin_BoolToString", + }, + } + + // Build our own semantic checks that we always run + tv := &TypeCheck{Scope: scope, Implicit: implicitMap} + ic := &IdentifierCheck{Scope: scope} + + // Build up the semantic checks for execution + checks := make( + []SemanticChecker, + len(config.SemanticChecks), + len(config.SemanticChecks)+2) + copy(checks, config.SemanticChecks) + checks = append(checks, ic.Visit) + checks = append(checks, tv.Visit) + + // Run the semantic checks + for _, check := range checks { + if err := check(root); err != nil { + return nil, ast.TypeInvalid, err + } + } + + // Execute + v := &evalVisitor{Scope: scope} + return v.Visit(root) +} + +// EvalNode is the interface that must be implemented by any ast.Node +// to support evaluation. This will be called in visitor pattern order. +// The result of each call to Eval is automatically pushed onto the +// stack as a LiteralNode. Pop elements off the stack to get child +// values. +type EvalNode interface { + Eval(ast.Scope, *ast.Stack) (interface{}, ast.Type, error) +} + +type evalVisitor struct { + Scope ast.Scope + Stack ast.Stack + + err error + lock sync.Mutex +} + +func (v *evalVisitor) Visit(root ast.Node) (interface{}, ast.Type, error) { + // Run the actual visitor pattern + root.Accept(v.visit) + + // Get our result and clear out everything else + var result *ast.LiteralNode + if v.Stack.Len() > 0 { + result = v.Stack.Pop().(*ast.LiteralNode) + } else { + result = new(ast.LiteralNode) + } + resultErr := v.err + if resultErr == errExitUnknown { + // This means the return value is unknown and we used the error + // as an early exit mechanism. Reset since the value on the stack + // should be the unknown value. + resultErr = nil + } + + // Clear everything else so we aren't just dangling + v.Stack.Reset() + v.err = nil + + t, err := result.Type(v.Scope) + if err != nil { + return nil, ast.TypeInvalid, err + } + + return result.Value, t, resultErr +} + +func (v *evalVisitor) visit(raw ast.Node) ast.Node { + if v.err != nil { + return raw + } + + en, err := evalNode(raw) + if err != nil { + v.err = err + return raw + } + + out, outType, err := en.Eval(v.Scope, &v.Stack) + if err != nil { + v.err = err + return raw + } + + v.Stack.Push(&ast.LiteralNode{ + Value: out, + Typex: outType, + }) + + if outType == ast.TypeUnknown { + // Halt immediately + v.err = errExitUnknown + return raw + } + + return raw +} + +// evalNode is a private function that returns an EvalNode for built-in +// types as well as any other EvalNode implementations. +func evalNode(raw ast.Node) (EvalNode, error) { + switch n := raw.(type) { + case *ast.Index: + return &evalIndex{n}, nil + case *ast.Call: + return &evalCall{n}, nil + case *ast.Conditional: + return &evalConditional{n}, nil + case *ast.Output: + return &evalOutput{n}, nil + case *ast.LiteralNode: + return &evalLiteralNode{n}, nil + case *ast.VariableAccess: + return &evalVariableAccess{n}, nil + default: + en, ok := n.(EvalNode) + if !ok { + return nil, fmt.Errorf("node doesn't support evaluation: %#v", raw) + } + + return en, nil + } +} + +type evalCall struct{ *ast.Call } + +func (v *evalCall) Eval(s ast.Scope, stack *ast.Stack) (interface{}, ast.Type, error) { + // Look up the function in the map + function, ok := s.LookupFunc(v.Func) + if !ok { + return nil, ast.TypeInvalid, fmt.Errorf( + "unknown function called: %s", v.Func) + } + + // The arguments are on the stack in reverse order, so pop them off. + args := make([]interface{}, len(v.Args)) + for i, _ := range v.Args { + node := stack.Pop().(*ast.LiteralNode) + if node.IsUnknown() { + // If any arguments are unknown then the result is automatically unknown + return UnknownValue, ast.TypeUnknown, nil + } + args[len(v.Args)-1-i] = node.Value + } + + // Call the function + result, err := function.Callback(args) + if err != nil { + return nil, ast.TypeInvalid, fmt.Errorf("%s: %s", v.Func, err) + } + + return result, function.ReturnType, nil +} + +type evalConditional struct{ *ast.Conditional } + +func (v *evalConditional) Eval(s ast.Scope, stack *ast.Stack) (interface{}, ast.Type, error) { + // On the stack we have literal nodes representing the resulting values + // of the condition, true and false expressions, but they are in reverse + // order. + falseLit := stack.Pop().(*ast.LiteralNode) + trueLit := stack.Pop().(*ast.LiteralNode) + condLit := stack.Pop().(*ast.LiteralNode) + + if condLit.IsUnknown() { + // If our conditional is unknown then our result is also unknown + return UnknownValue, ast.TypeUnknown, nil + } + + if condLit.Value.(bool) { + return trueLit.Value, trueLit.Typex, nil + } else { + return falseLit.Value, trueLit.Typex, nil + } +} + +type evalIndex struct{ *ast.Index } + +func (v *evalIndex) Eval(scope ast.Scope, stack *ast.Stack) (interface{}, ast.Type, error) { + key := stack.Pop().(*ast.LiteralNode) + target := stack.Pop().(*ast.LiteralNode) + + variableName := v.Index.Target.(*ast.VariableAccess).Name + + if key.IsUnknown() { + // If our key is unknown then our result is also unknown + return UnknownValue, ast.TypeUnknown, nil + } + + // For target, we'll accept collections containing unknown values but + // we still need to catch when the collection itself is unknown, shallowly. + if target.Typex == ast.TypeUnknown { + return UnknownValue, ast.TypeUnknown, nil + } + + switch target.Typex { + case ast.TypeList: + return v.evalListIndex(variableName, target.Value, key.Value) + case ast.TypeMap: + return v.evalMapIndex(variableName, target.Value, key.Value) + default: + return nil, ast.TypeInvalid, fmt.Errorf( + "target %q for indexing must be ast.TypeList or ast.TypeMap, is %s", + variableName, target.Typex) + } +} + +func (v *evalIndex) evalListIndex(variableName string, target interface{}, key interface{}) (interface{}, ast.Type, error) { + // We assume type checking was already done and we can assume that target + // is a list and key is an int + list, ok := target.([]ast.Variable) + if !ok { + return nil, ast.TypeInvalid, fmt.Errorf( + "cannot cast target to []Variable, is: %T", target) + } + + keyInt, ok := key.(int) + if !ok { + return nil, ast.TypeInvalid, fmt.Errorf( + "cannot cast key to int, is: %T", key) + } + + if len(list) == 0 { + return nil, ast.TypeInvalid, fmt.Errorf("list is empty") + } + + if keyInt < 0 || len(list) < keyInt+1 { + return nil, ast.TypeInvalid, fmt.Errorf( + "index %d out of range for list %s (max %d)", + keyInt, variableName, len(list)) + } + + returnVal := list[keyInt].Value + returnType := list[keyInt].Type + return returnVal, returnType, nil +} + +func (v *evalIndex) evalMapIndex(variableName string, target interface{}, key interface{}) (interface{}, ast.Type, error) { + // We assume type checking was already done and we can assume that target + // is a map and key is a string + vmap, ok := target.(map[string]ast.Variable) + if !ok { + return nil, ast.TypeInvalid, fmt.Errorf( + "cannot cast target to map[string]Variable, is: %T", target) + } + + keyString, ok := key.(string) + if !ok { + return nil, ast.TypeInvalid, fmt.Errorf( + "cannot cast key to string, is: %T", key) + } + + if len(vmap) == 0 { + return nil, ast.TypeInvalid, fmt.Errorf("map is empty") + } + + value, ok := vmap[keyString] + if !ok { + return nil, ast.TypeInvalid, fmt.Errorf( + "key %q does not exist in map %s", keyString, variableName) + } + + return value.Value, value.Type, nil +} + +type evalOutput struct{ *ast.Output } + +func (v *evalOutput) Eval(s ast.Scope, stack *ast.Stack) (interface{}, ast.Type, error) { + // The expressions should all be on the stack in reverse + // order. So pop them off, reverse their order, and concatenate. + nodes := make([]*ast.LiteralNode, 0, len(v.Exprs)) + haveUnknown := false + for range v.Exprs { + n := stack.Pop().(*ast.LiteralNode) + nodes = append(nodes, n) + + // If we have any unknowns then the whole result is unknown + // (we must deal with this first, because the type checker can + // skip type conversions in the presence of unknowns, and thus + // any of our other nodes may be incorrectly typed.) + if n.IsUnknown() { + haveUnknown = true + } + } + + if haveUnknown { + return UnknownValue, ast.TypeUnknown, nil + } + + // Special case the single list and map + if len(nodes) == 1 { + switch t := nodes[0].Typex; t { + case ast.TypeList: + fallthrough + case ast.TypeMap: + fallthrough + case ast.TypeUnknown: + return nodes[0].Value, t, nil + } + } + + // Otherwise concatenate the strings + var buf bytes.Buffer + for i := len(nodes) - 1; i >= 0; i-- { + if nodes[i].Typex != ast.TypeString { + return nil, ast.TypeInvalid, fmt.Errorf( + "invalid output with %s value at index %d: %#v", + nodes[i].Typex, + i, + nodes[i].Value, + ) + } + buf.WriteString(nodes[i].Value.(string)) + } + + return buf.String(), ast.TypeString, nil +} + +type evalLiteralNode struct{ *ast.LiteralNode } + +func (v *evalLiteralNode) Eval(ast.Scope, *ast.Stack) (interface{}, ast.Type, error) { + return v.Value, v.Typex, nil +} + +type evalVariableAccess struct{ *ast.VariableAccess } + +func (v *evalVariableAccess) Eval(scope ast.Scope, _ *ast.Stack) (interface{}, ast.Type, error) { + // Look up the variable in the map + variable, ok := scope.LookupVar(v.Name) + if !ok { + return nil, ast.TypeInvalid, fmt.Errorf( + "unknown variable accessed: %s", v.Name) + } + + return variable.Value, variable.Type, nil +} -- cgit v1.2.3