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expression.go
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expression.go
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package hclsyntax
import (
"fmt"
"sync"
"github.com/kage-cloud/hcl/v2"
"github.com/kage-cloud/hcl/v2/ext/customdecode"
"github.com/zclconf/go-cty/cty"
"github.com/zclconf/go-cty/cty/convert"
"github.com/zclconf/go-cty/cty/function"
)
// Expression is the abstract type for nodes that behave as HCL expressions.
type Expression interface {
Node
// The hcl.Expression methods are duplicated here, rather than simply
// embedded, because both Node and hcl.Expression have a Range method
// and so they conflict.
Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnostics)
Variables() []hcl.Traversal
StartRange() hcl.Range
}
// Assert that Expression implements hcl.Expression
var assertExprImplExpr hcl.Expression = Expression(nil)
// LiteralValueExpr is an expression that just always returns a given value.
type LiteralValueExpr struct {
Val cty.Value
SrcRange hcl.Range
}
func (e *LiteralValueExpr) walkChildNodes(w internalWalkFunc) {
// Literal values have no child nodes
}
func (e *LiteralValueExpr) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnostics) {
return e.Val, nil
}
func (e *LiteralValueExpr) Range() hcl.Range {
return e.SrcRange
}
func (e *LiteralValueExpr) StartRange() hcl.Range {
return e.SrcRange
}
// Implementation for hcl.AbsTraversalForExpr.
func (e *LiteralValueExpr) AsTraversal() hcl.Traversal {
// This one's a little weird: the contract for AsTraversal is to interpret
// an expression as if it were traversal syntax, and traversal syntax
// doesn't have the special keywords "null", "true", and "false" so these
// are expected to be treated like variables in that case.
// Since our parser already turned them into LiteralValueExpr by the time
// we get here, we need to undo this and infer the name that would've
// originally led to our value.
// We don't do anything for any other values, since they don't overlap
// with traversal roots.
if e.Val.IsNull() {
// In practice the parser only generates null values of the dynamic
// pseudo-type for literals, so we can safely assume that any null
// was orignally the keyword "null".
return hcl.Traversal{
hcl.TraverseRoot{
Name: "null",
SrcRange: e.SrcRange,
},
}
}
switch e.Val {
case cty.True:
return hcl.Traversal{
hcl.TraverseRoot{
Name: "true",
SrcRange: e.SrcRange,
},
}
case cty.False:
return hcl.Traversal{
hcl.TraverseRoot{
Name: "false",
SrcRange: e.SrcRange,
},
}
default:
// No traversal is possible for any other value.
return nil
}
}
// ScopeTraversalExpr is an Expression that retrieves a value from the scope
// using a traversal.
type ScopeTraversalExpr struct {
Traversal hcl.Traversal
SrcRange hcl.Range
}
func (e *ScopeTraversalExpr) walkChildNodes(w internalWalkFunc) {
// Scope traversals have no child nodes
}
func (e *ScopeTraversalExpr) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnostics) {
val, diags := e.Traversal.TraverseAbs(ctx)
setDiagEvalContext(diags, e, ctx)
return val, diags
}
func (e *ScopeTraversalExpr) Range() hcl.Range {
return e.SrcRange
}
func (e *ScopeTraversalExpr) StartRange() hcl.Range {
return e.SrcRange
}
// Implementation for hcl.AbsTraversalForExpr.
func (e *ScopeTraversalExpr) AsTraversal() hcl.Traversal {
return e.Traversal
}
// RelativeTraversalExpr is an Expression that retrieves a value from another
// value using a _relative_ traversal.
type RelativeTraversalExpr struct {
Source Expression
Traversal hcl.Traversal
SrcRange hcl.Range
}
func (e *RelativeTraversalExpr) walkChildNodes(w internalWalkFunc) {
w(e.Source)
}
func (e *RelativeTraversalExpr) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnostics) {
src, diags := e.Source.Value(ctx)
ret, travDiags := e.Traversal.TraverseRel(src)
setDiagEvalContext(travDiags, e, ctx)
diags = append(diags, travDiags...)
return ret, diags
}
func (e *RelativeTraversalExpr) Range() hcl.Range {
return e.SrcRange
}
func (e *RelativeTraversalExpr) StartRange() hcl.Range {
return e.SrcRange
}
// Implementation for hcl.AbsTraversalForExpr.
func (e *RelativeTraversalExpr) AsTraversal() hcl.Traversal {
// We can produce a traversal only if our source can.
st, diags := hcl.AbsTraversalForExpr(e.Source)
if diags.HasErrors() {
return nil
}
ret := make(hcl.Traversal, len(st)+len(e.Traversal))
copy(ret, st)
copy(ret[len(st):], e.Traversal)
return ret
}
// FunctionCallExpr is an Expression that calls a function from the EvalContext
// and returns its result.
type FunctionCallExpr struct {
Name string
Args []Expression
// If true, the final argument should be a tuple, list or set which will
// expand to be one argument per element.
ExpandFinal bool
NameRange hcl.Range
OpenParenRange hcl.Range
CloseParenRange hcl.Range
}
func (e *FunctionCallExpr) walkChildNodes(w internalWalkFunc) {
for _, arg := range e.Args {
w(arg)
}
}
func (e *FunctionCallExpr) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnostics) {
var diags hcl.Diagnostics
var f function.Function
exists := false
hasNonNilMap := false
thisCtx := ctx
for thisCtx != nil {
if thisCtx.Functions == nil {
thisCtx = thisCtx.Parent()
continue
}
hasNonNilMap = true
f, exists = thisCtx.Functions[e.Name]
if exists {
break
}
thisCtx = thisCtx.Parent()
}
if !exists {
if !hasNonNilMap {
return cty.DynamicVal, hcl.Diagnostics{
{
Severity: hcl.DiagError,
Summary: "Function calls not allowed",
Detail: "Functions may not be called here.",
Subject: e.Range().Ptr(),
Expression: e,
EvalContext: ctx,
},
}
}
avail := make([]string, 0, len(ctx.Functions))
for name := range ctx.Functions {
avail = append(avail, name)
}
suggestion := nameSuggestion(e.Name, avail)
if suggestion != "" {
suggestion = fmt.Sprintf(" Did you mean %q?", suggestion)
}
return cty.DynamicVal, hcl.Diagnostics{
{
Severity: hcl.DiagError,
Summary: "Call to unknown function",
Detail: fmt.Sprintf("There is no function named %q.%s", e.Name, suggestion),
Subject: &e.NameRange,
Context: e.Range().Ptr(),
Expression: e,
EvalContext: ctx,
},
}
}
params := f.Params()
varParam := f.VarParam()
args := e.Args
if e.ExpandFinal {
if len(args) < 1 {
// should never happen if the parser is behaving
panic("ExpandFinal set on function call with no arguments")
}
expandExpr := args[len(args)-1]
expandVal, expandDiags := expandExpr.Value(ctx)
diags = append(diags, expandDiags...)
if expandDiags.HasErrors() {
return cty.DynamicVal, diags
}
switch {
case expandVal.Type().IsTupleType() || expandVal.Type().IsListType() || expandVal.Type().IsSetType():
if expandVal.IsNull() {
diags = append(diags, &hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: "Invalid expanding argument value",
Detail: "The expanding argument (indicated by ...) must not be null.",
Subject: expandExpr.Range().Ptr(),
Context: e.Range().Ptr(),
Expression: expandExpr,
EvalContext: ctx,
})
return cty.DynamicVal, diags
}
if !expandVal.IsKnown() {
return cty.DynamicVal, diags
}
newArgs := make([]Expression, 0, (len(args)-1)+expandVal.LengthInt())
newArgs = append(newArgs, args[:len(args)-1]...)
it := expandVal.ElementIterator()
for it.Next() {
_, val := it.Element()
newArgs = append(newArgs, &LiteralValueExpr{
Val: val,
SrcRange: expandExpr.Range(),
})
}
args = newArgs
default:
diags = append(diags, &hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: "Invalid expanding argument value",
Detail: "The expanding argument (indicated by ...) must be of a tuple, list, or set type.",
Subject: expandExpr.Range().Ptr(),
Context: e.Range().Ptr(),
Expression: expandExpr,
EvalContext: ctx,
})
return cty.DynamicVal, diags
}
}
if len(args) < len(params) {
missing := params[len(args)]
qual := ""
if varParam != nil {
qual = " at least"
}
return cty.DynamicVal, hcl.Diagnostics{
{
Severity: hcl.DiagError,
Summary: "Not enough function arguments",
Detail: fmt.Sprintf(
"Function %q expects%s %d argument(s). Missing value for %q.",
e.Name, qual, len(params), missing.Name,
),
Subject: &e.CloseParenRange,
Context: e.Range().Ptr(),
Expression: e,
EvalContext: ctx,
},
}
}
if varParam == nil && len(args) > len(params) {
return cty.DynamicVal, hcl.Diagnostics{
{
Severity: hcl.DiagError,
Summary: "Too many function arguments",
Detail: fmt.Sprintf(
"Function %q expects only %d argument(s).",
e.Name, len(params),
),
Subject: args[len(params)].StartRange().Ptr(),
Context: e.Range().Ptr(),
Expression: e,
EvalContext: ctx,
},
}
}
argVals := make([]cty.Value, len(args))
for i, argExpr := range args {
var param *function.Parameter
if i < len(params) {
param = ¶ms[i]
} else {
param = varParam
}
var val cty.Value
if decodeFn := customdecode.CustomExpressionDecoderForType(param.Type); decodeFn != nil {
var argDiags hcl.Diagnostics
val, argDiags = decodeFn(argExpr, ctx)
diags = append(diags, argDiags...)
if val == cty.NilVal {
val = cty.UnknownVal(param.Type)
}
} else {
var argDiags hcl.Diagnostics
val, argDiags = argExpr.Value(ctx)
if len(argDiags) > 0 {
diags = append(diags, argDiags...)
}
// Try to convert our value to the parameter type
var err error
val, err = convert.Convert(val, param.Type)
if err != nil {
diags = append(diags, &hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: "Invalid function argument",
Detail: fmt.Sprintf(
"Invalid value for %q parameter: %s.",
param.Name, err,
),
Subject: argExpr.StartRange().Ptr(),
Context: e.Range().Ptr(),
Expression: argExpr,
EvalContext: ctx,
})
}
}
argVals[i] = val
}
if diags.HasErrors() {
// Don't try to execute the function if we already have errors with
// the arguments, because the result will probably be a confusing
// error message.
return cty.DynamicVal, diags
}
resultVal, err := f.Call(argVals)
if err != nil {
switch terr := err.(type) {
case function.ArgError:
i := terr.Index
var param *function.Parameter
if i < len(params) {
param = ¶ms[i]
} else {
param = varParam
}
argExpr := e.Args[i]
// TODO: we should also unpick a PathError here and show the
// path to the deep value where the error was detected.
diags = append(diags, &hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: "Invalid function argument",
Detail: fmt.Sprintf(
"Invalid value for %q parameter: %s.",
param.Name, err,
),
Subject: argExpr.StartRange().Ptr(),
Context: e.Range().Ptr(),
Expression: argExpr,
EvalContext: ctx,
})
default:
diags = append(diags, &hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: "Error in function call",
Detail: fmt.Sprintf(
"Call to function %q failed: %s.",
e.Name, err,
),
Subject: e.StartRange().Ptr(),
Context: e.Range().Ptr(),
Expression: e,
EvalContext: ctx,
})
}
return cty.DynamicVal, diags
}
return resultVal, diags
}
func (e *FunctionCallExpr) Range() hcl.Range {
return hcl.RangeBetween(e.NameRange, e.CloseParenRange)
}
func (e *FunctionCallExpr) StartRange() hcl.Range {
return hcl.RangeBetween(e.NameRange, e.OpenParenRange)
}
// Implementation for hcl.ExprCall.
func (e *FunctionCallExpr) ExprCall() *hcl.StaticCall {
ret := &hcl.StaticCall{
Name: e.Name,
NameRange: e.NameRange,
Arguments: make([]hcl.Expression, len(e.Args)),
ArgsRange: hcl.RangeBetween(e.OpenParenRange, e.CloseParenRange),
}
// Need to convert our own Expression objects into hcl.Expression.
for i, arg := range e.Args {
ret.Arguments[i] = arg
}
return ret
}
type ConditionalExpr struct {
Condition Expression
TrueResult Expression
FalseResult Expression
SrcRange hcl.Range
}
func (e *ConditionalExpr) walkChildNodes(w internalWalkFunc) {
w(e.Condition)
w(e.TrueResult)
w(e.FalseResult)
}
func (e *ConditionalExpr) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnostics) {
trueResult, trueDiags := e.TrueResult.Value(ctx)
falseResult, falseDiags := e.FalseResult.Value(ctx)
var diags hcl.Diagnostics
resultType := cty.DynamicPseudoType
convs := make([]convert.Conversion, 2)
switch {
// If either case is a dynamic null value (which would result from a
// literal null in the config), we know that it can convert to the expected
// type of the opposite case, and we don't need to speculatively reduce the
// final result type to DynamicPseudoType.
// If we know that either Type is a DynamicPseudoType, we can be certain
// that the other value can convert since it's a pass-through, and we don't
// need to unify the types. If the final evaluation results in the dynamic
// value being returned, there's no conversion we can do, so we return the
// value directly.
case trueResult.RawEquals(cty.NullVal(cty.DynamicPseudoType)):
resultType = falseResult.Type()
convs[0] = convert.GetConversionUnsafe(cty.DynamicPseudoType, resultType)
case falseResult.RawEquals(cty.NullVal(cty.DynamicPseudoType)):
resultType = trueResult.Type()
convs[1] = convert.GetConversionUnsafe(cty.DynamicPseudoType, resultType)
case trueResult.Type() == cty.DynamicPseudoType, falseResult.Type() == cty.DynamicPseudoType:
// the final resultType type is still unknown
// we don't need to get the conversion, because both are a noop.
default:
// Try to find a type that both results can be converted to.
resultType, convs = convert.UnifyUnsafe([]cty.Type{trueResult.Type(), falseResult.Type()})
}
if resultType == cty.NilType {
return cty.DynamicVal, hcl.Diagnostics{
{
Severity: hcl.DiagError,
Summary: "Inconsistent conditional result types",
Detail: fmt.Sprintf(
// FIXME: Need a helper function for showing natural-language type diffs,
// since this will generate some useless messages in some cases, like
// "These expressions are object and object respectively" if the
// object types don't exactly match.
"The true and false result expressions must have consistent types. The given expressions are %s and %s, respectively.",
trueResult.Type().FriendlyName(), falseResult.Type().FriendlyName(),
),
Subject: hcl.RangeBetween(e.TrueResult.Range(), e.FalseResult.Range()).Ptr(),
Context: &e.SrcRange,
Expression: e,
EvalContext: ctx,
},
}
}
condResult, condDiags := e.Condition.Value(ctx)
diags = append(diags, condDiags...)
if condResult.IsNull() {
diags = append(diags, &hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: "Null condition",
Detail: "The condition value is null. Conditions must either be true or false.",
Subject: e.Condition.Range().Ptr(),
Context: &e.SrcRange,
Expression: e.Condition,
EvalContext: ctx,
})
return cty.UnknownVal(resultType), diags
}
if !condResult.IsKnown() {
return cty.UnknownVal(resultType), diags
}
condResult, err := convert.Convert(condResult, cty.Bool)
if err != nil {
diags = append(diags, &hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: "Incorrect condition type",
Detail: fmt.Sprintf("The condition expression must be of type bool."),
Subject: e.Condition.Range().Ptr(),
Context: &e.SrcRange,
Expression: e.Condition,
EvalContext: ctx,
})
return cty.UnknownVal(resultType), diags
}
if condResult.True() {
diags = append(diags, trueDiags...)
if convs[0] != nil {
var err error
trueResult, err = convs[0](trueResult)
if err != nil {
// Unsafe conversion failed with the concrete result value
diags = append(diags, &hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: "Inconsistent conditional result types",
Detail: fmt.Sprintf(
"The true result value has the wrong type: %s.",
err.Error(),
),
Subject: e.TrueResult.Range().Ptr(),
Context: &e.SrcRange,
Expression: e.TrueResult,
EvalContext: ctx,
})
trueResult = cty.UnknownVal(resultType)
}
}
return trueResult, diags
} else {
diags = append(diags, falseDiags...)
if convs[1] != nil {
var err error
falseResult, err = convs[1](falseResult)
if err != nil {
// Unsafe conversion failed with the concrete result value
diags = append(diags, &hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: "Inconsistent conditional result types",
Detail: fmt.Sprintf(
"The false result value has the wrong type: %s.",
err.Error(),
),
Subject: e.FalseResult.Range().Ptr(),
Context: &e.SrcRange,
Expression: e.FalseResult,
EvalContext: ctx,
})
falseResult = cty.UnknownVal(resultType)
}
}
return falseResult, diags
}
}
func (e *ConditionalExpr) Range() hcl.Range {
return e.SrcRange
}
func (e *ConditionalExpr) StartRange() hcl.Range {
return e.Condition.StartRange()
}
type IndexExpr struct {
Collection Expression
Key Expression
SrcRange hcl.Range
OpenRange hcl.Range
BracketRange hcl.Range
}
func (e *IndexExpr) walkChildNodes(w internalWalkFunc) {
w(e.Collection)
w(e.Key)
}
func (e *IndexExpr) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnostics) {
var diags hcl.Diagnostics
coll, collDiags := e.Collection.Value(ctx)
key, keyDiags := e.Key.Value(ctx)
diags = append(diags, collDiags...)
diags = append(diags, keyDiags...)
val, indexDiags := hcl.Index(coll, key, &e.BracketRange)
setDiagEvalContext(indexDiags, e, ctx)
diags = append(diags, indexDiags...)
return val, diags
}
func (e *IndexExpr) Range() hcl.Range {
return e.SrcRange
}
func (e *IndexExpr) StartRange() hcl.Range {
return e.OpenRange
}
type TupleConsExpr struct {
Exprs []Expression
SrcRange hcl.Range
OpenRange hcl.Range
}
func (e *TupleConsExpr) walkChildNodes(w internalWalkFunc) {
for _, expr := range e.Exprs {
w(expr)
}
}
func (e *TupleConsExpr) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnostics) {
var vals []cty.Value
var diags hcl.Diagnostics
vals = make([]cty.Value, len(e.Exprs))
for i, expr := range e.Exprs {
val, valDiags := expr.Value(ctx)
vals[i] = val
diags = append(diags, valDiags...)
}
return cty.TupleVal(vals), diags
}
func (e *TupleConsExpr) Range() hcl.Range {
return e.SrcRange
}
func (e *TupleConsExpr) StartRange() hcl.Range {
return e.OpenRange
}
// Implementation for hcl.ExprList
func (e *TupleConsExpr) ExprList() []hcl.Expression {
ret := make([]hcl.Expression, len(e.Exprs))
for i, expr := range e.Exprs {
ret[i] = expr
}
return ret
}
type ObjectConsExpr struct {
Items []ObjectConsItem
SrcRange hcl.Range
OpenRange hcl.Range
}
type ObjectConsItem struct {
KeyExpr Expression
ValueExpr Expression
}
func (e *ObjectConsExpr) walkChildNodes(w internalWalkFunc) {
for _, item := range e.Items {
w(item.KeyExpr)
w(item.ValueExpr)
}
}
func (e *ObjectConsExpr) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnostics) {
var vals map[string]cty.Value
var diags hcl.Diagnostics
// This will get set to true if we fail to produce any of our keys,
// either because they are actually unknown or if the evaluation produces
// errors. In all of these case we must return DynamicPseudoType because
// we're unable to know the full set of keys our object has, and thus
// we can't produce a complete value of the intended type.
//
// We still evaluate all of the item keys and values to make sure that we
// get as complete as possible a set of diagnostics.
known := true
vals = make(map[string]cty.Value, len(e.Items))
for _, item := range e.Items {
key, keyDiags := item.KeyExpr.Value(ctx)
diags = append(diags, keyDiags...)
val, valDiags := item.ValueExpr.Value(ctx)
diags = append(diags, valDiags...)
if keyDiags.HasErrors() {
known = false
continue
}
if key.IsNull() {
diags = append(diags, &hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: "Null value as key",
Detail: "Can't use a null value as a key.",
Subject: item.ValueExpr.Range().Ptr(),
Expression: item.KeyExpr,
EvalContext: ctx,
})
known = false
continue
}
var err error
key, err = convert.Convert(key, cty.String)
if err != nil {
diags = append(diags, &hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: "Incorrect key type",
Detail: fmt.Sprintf("Can't use this value as a key: %s.", err.Error()),
Subject: item.KeyExpr.Range().Ptr(),
Expression: item.KeyExpr,
EvalContext: ctx,
})
known = false
continue
}
if !key.IsKnown() {
known = false
continue
}
keyStr := key.AsString()
vals[keyStr] = val
}
if !known {
return cty.DynamicVal, diags
}
return cty.ObjectVal(vals), diags
}
func (e *ObjectConsExpr) Range() hcl.Range {
return e.SrcRange
}
func (e *ObjectConsExpr) StartRange() hcl.Range {
return e.OpenRange
}
// Implementation for hcl.ExprMap
func (e *ObjectConsExpr) ExprMap() []hcl.KeyValuePair {
ret := make([]hcl.KeyValuePair, len(e.Items))
for i, item := range e.Items {
ret[i] = hcl.KeyValuePair{
Key: item.KeyExpr,
Value: item.ValueExpr,
}
}
return ret
}
// ObjectConsKeyExpr is a special wrapper used only for ObjectConsExpr keys,
// which deals with the special case that a naked identifier in that position
// must be interpreted as a literal string rather than evaluated directly.
type ObjectConsKeyExpr struct {
Wrapped Expression
ForceNonLiteral bool
}
func (e *ObjectConsKeyExpr) literalName() string {
// This is our logic for deciding whether to behave like a literal string.
// We lean on our AbsTraversalForExpr implementation here, which already
// deals with some awkward cases like the expression being the result
// of the keywords "null", "true" and "false" which we'd want to interpret
// as keys here too.
return hcl.ExprAsKeyword(e.Wrapped)
}
func (e *ObjectConsKeyExpr) walkChildNodes(w internalWalkFunc) {
// We only treat our wrapped expression as a real expression if we're
// not going to interpret it as a literal.
if e.literalName() == "" {
w(e.Wrapped)
}
}
func (e *ObjectConsKeyExpr) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnostics) {
// Because we accept a naked identifier as a literal key rather than a
// reference, it's confusing to accept a traversal containing periods
// here since we can't tell if the user intends to create a key with
// periods or actually reference something. To avoid confusing downstream
// errors we'll just prohibit a naked multi-step traversal here and
// require the user to state their intent more clearly.
// (This is handled at evaluation time rather than parse time because
// an application using static analysis _can_ accept a naked multi-step
// traversal here, if desired.)
if !e.ForceNonLiteral {
if travExpr, isTraversal := e.Wrapped.(*ScopeTraversalExpr); isTraversal && len(travExpr.Traversal) > 1 {
var diags hcl.Diagnostics
diags = append(diags, &hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: "Ambiguous attribute key",
Detail: "If this expression is intended to be a reference, wrap it in parentheses. If it's instead intended as a literal name containing periods, wrap it in quotes to create a string literal.",
Subject: e.Range().Ptr(),
})
return cty.DynamicVal, diags
}
if ln := e.literalName(); ln != "" {
return cty.StringVal(ln), nil
}
}
return e.Wrapped.Value(ctx)
}
func (e *ObjectConsKeyExpr) Range() hcl.Range {
return e.Wrapped.Range()
}
func (e *ObjectConsKeyExpr) StartRange() hcl.Range {
return e.Wrapped.StartRange()
}
// Implementation for hcl.AbsTraversalForExpr.
func (e *ObjectConsKeyExpr) AsTraversal() hcl.Traversal {
// If we're forcing a non-literal then we can never be interpreted
// as a traversal.
if e.ForceNonLiteral {
return nil
}
// We can produce a traversal only if our wrappee can.
st, diags := hcl.AbsTraversalForExpr(e.Wrapped)
if diags.HasErrors() {
return nil
}
return st
}
func (e *ObjectConsKeyExpr) UnwrapExpression() Expression {
return e.Wrapped
}
// ForExpr represents iteration constructs:
//
// tuple = [for i, v in list: upper(v) if i > 2]
// object = {for k, v in map: k => upper(v)}
// object_of_tuples = {for v in list: v.key: v...}
type ForExpr struct {
KeyVar string // empty if ignoring the key
ValVar string
CollExpr Expression
KeyExpr Expression // nil when producing a tuple
ValExpr Expression
CondExpr Expression // null if no "if" clause is present
Group bool // set if the ellipsis is used on the value in an object for
SrcRange hcl.Range
OpenRange hcl.Range
CloseRange hcl.Range
}
func (e *ForExpr) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnostics) {
var diags hcl.Diagnostics
collVal, collDiags := e.CollExpr.Value(ctx)
diags = append(diags, collDiags...)
if collVal.IsNull() {
diags = append(diags, &hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: "Iteration over null value",
Detail: "A null value cannot be used as the collection in a 'for' expression.",
Subject: e.CollExpr.Range().Ptr(),
Context: &e.SrcRange,
Expression: e.CollExpr,
EvalContext: ctx,
})
return cty.DynamicVal, diags
}
if collVal.Type() == cty.DynamicPseudoType {
return cty.DynamicVal, diags
}
if !collVal.CanIterateElements() {
diags = append(diags, &hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: "Iteration over non-iterable value",
Detail: fmt.Sprintf(
"A value of type %s cannot be used as the collection in a 'for' expression.",
collVal.Type().FriendlyName(),
),
Subject: e.CollExpr.Range().Ptr(),
Context: &e.SrcRange,
Expression: e.CollExpr,
EvalContext: ctx,
})
return cty.DynamicVal, diags
}
if !collVal.IsKnown() {
return cty.DynamicVal, diags
}
// Before we start we'll do an early check to see if any CondExpr we've
// been given is of the wrong type. This isn't 100% reliable (it may
// be DynamicVal until real values are given) but it should catch some
// straightforward cases and prevent a barrage of repeated errors.
if e.CondExpr != nil {
childCtx := ctx.NewChild()
childCtx.Variables = map[string]cty.Value{}
if e.KeyVar != "" {
childCtx.Variables[e.KeyVar] = cty.DynamicVal
}
childCtx.Variables[e.ValVar] = cty.DynamicVal
result, condDiags := e.CondExpr.Value(childCtx)
diags = append(diags, condDiags...)
if result.IsNull() {
diags = append(diags, &hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: "Condition is null",
Detail: "The value of the 'if' clause must not be null.",
Subject: e.CondExpr.Range().Ptr(),
Context: &e.SrcRange,
Expression: e.CondExpr,
EvalContext: ctx,
})
return cty.DynamicVal, diags
}
_, err := convert.Convert(result, cty.Bool)
if err != nil {
diags = append(diags, &hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: "Invalid 'for' condition",
Detail: fmt.Sprintf("The 'if' clause value is invalid: %s.", err.Error()),
Subject: e.CondExpr.Range().Ptr(),
Context: &e.SrcRange,
Expression: e.CondExpr,
EvalContext: ctx,
})
return cty.DynamicVal, diags
}