Support complex index expressions

decoder/expr_any_completion.go

@@ -143,5 +143,7 @@ func (a Any) completeNonComplexExprAtPos(ctx context.Context, pos hcl.Pos) []lan
 	}
 	candidates = append(candidates, lt.CompletionAtPos(ctx, pos)...)
 
+	candidates = append(candidates, a.complexIndex(ctx, pos)...)
+
 	return candidates
 }

decoder/expr_any_completion_test.go

@@ -524,7 +524,7 @@ func TestCompletionAtPos_exprAny_functions(t *testing.T) {
 						Start:    hcl.Pos{Line: 2, Column: 5, Byte: 27},
 						End:      hcl.Pos{Line: 2, Column: 15, Byte: 37},
 					},
-					Type: cty.List(cty.String),
+					Type: cty.Map(cty.String),
 					NestedTargets: reference.Targets{
 						{
 							Addr: lang.Address{
@@ -560,6 +560,95 @@ func TestCompletionAtPos_exprAny_functions(t *testing.T) {
 						Snippet: `var.map["foo"]`,
 					},
 				},
+				{
+					Label:  `var.map`,
+					Detail: "map of string",
+					Kind:   lang.ReferenceCandidateKind,
+					TextEdit: lang.TextEdit{
+						Range: hcl.Range{
+							Filename: "test.tf",
+							Start:    hcl.Pos{Line: 1, Column: 22, Byte: 21},
+							End:      hcl.Pos{Line: 1, Column: 22, Byte: 21},
+						},
+						NewText: `var.map`,
+						Snippet: `var.map`,
+					},
+				},
+				{
+					Label:       "element",
+					Detail:      "element(list dynamic, index number) dynamic",
+					Description: lang.Markdown("`element` retrieves a single element from a list."),
+					Kind:        lang.FunctionCandidateKind,
+					TextEdit: lang.TextEdit{
+						NewText: "element()",
+						Snippet: "element(${0})",
+						Range: hcl.Range{
+							Filename: "test.tf",
+							Start:    hcl.Pos{Line: 1, Column: 22, Byte: 21},
+							End:      hcl.Pos{Line: 1, Column: 22, Byte: 21},
+						},
+					},
+				},
+				{
+					Label:       "join",
+					Detail:      "join(separator string, …lists list of string) string",
+					Description: lang.Markdown("`join` produces a string by concatenating together all elements of a given list of strings with the given delimiter."),
+					Kind:        lang.FunctionCandidateKind,
+					TextEdit: lang.TextEdit{
+						NewText: "join()",
+						Snippet: "join(${0})",
+						Range: hcl.Range{
+							Filename: "test.tf",
+							Start:    hcl.Pos{Line: 1, Column: 22, Byte: 21},
+							End:      hcl.Pos{Line: 1, Column: 22, Byte: 21},
+						},
+					},
+				},
+				{
+					Label:       "keys",
+					Detail:      "keys(inputMap dynamic) dynamic",
+					Description: lang.Markdown("`keys` takes a map and returns a list containing the keys from that map."),
+					Kind:        lang.FunctionCandidateKind,
+					TextEdit: lang.TextEdit{
+						NewText: "keys()",
+						Snippet: "keys(${0})",
+						Range: hcl.Range{
+							Filename: "test.tf",
+							Start:    hcl.Pos{Line: 1, Column: 22, Byte: 21},
+							End:      hcl.Pos{Line: 1, Column: 22, Byte: 21},
+						},
+					},
+				},
+				{
+					Label:       "log",
+					Detail:      "log(num number, base number) number",
+					Description: lang.Markdown("`log` returns the logarithm of a given number in a given base."),
+					Kind:        lang.FunctionCandidateKind,
+					TextEdit: lang.TextEdit{
+						NewText: "log()",
+						Snippet: "log(${0})",
+						Range: hcl.Range{
+							Filename: "test.tf",
+							Start:    hcl.Pos{Line: 1, Column: 22, Byte: 21},
+							End:      hcl.Pos{Line: 1, Column: 22, Byte: 21},
+						},
+					},
+				},
+				{
+					Label:       "lower",
+					Detail:      "lower(str string) string",
+					Description: lang.Markdown("`lower` converts all cased letters in the given string to lowercase."),
+					Kind:        lang.FunctionCandidateKind,
+					TextEdit: lang.TextEdit{
+						NewText: "lower()",
+						Snippet: "lower(${0})",
+						Range: hcl.Range{
+							Filename: "test.tf",
+							Start:    hcl.Pos{Line: 1, Column: 22, Byte: 21},
+							End:      hcl.Pos{Line: 1, Column: 22, Byte: 21},
+						},
+					},
+				},
 			}),
 		},
 		{

decoder/expr_any_hover.go

@@ -111,6 +111,10 @@ func (a Any) hoverNonComplexExprAtPos(ctx context.Context, pos hcl.Pos) *lang.Ho
 		return hoverData
 	}
 
+	if hoverData, ok := a.hoverIndexExprAtPos(ctx, pos); ok {
+		return hoverData
+	}
+
 	ref := Reference{
 		expr:    a.expr,
 		cons:    schema.Reference{OfType: a.cons.OfType},

decoder/expr_any_index.go

@@ -0,0 +1,77 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+package decoder
+
+import (
+	"context"
+
+	"github.com/hashicorp/hcl-lang/lang"
+	"github.com/hashicorp/hcl-lang/schema"
+	"github.com/hashicorp/hcl/v2"
+	"github.com/hashicorp/hcl/v2/hclsyntax"
+	"github.com/zclconf/go-cty/cty"
+)
+
+func (a Any) complexIndex(ctx context.Context, pos hcl.Pos) []lang.Candidate {
+	var candidates []lang.Candidate
+
+	cons := schema.AnyExpression{
+		OfType: cty.String, // TODO improve type (could be int)
+	}
+
+	switch eType := a.expr.(type) {
+	// An empty expression, e.g. `tags[]`, is a scope traversal expression
+	// with an empty index step.
+	case *hclsyntax.ScopeTraversalExpr:
+		if len(eType.Traversal) < 2 {
+			return candidates
+		}
+		// If the last part of the traversal is an index step,
+		// we start a new completion to enable completion of
+		// references and functions.
+		lastTraversal := eType.Traversal[len(eType.Traversal)-1]
+		if _, ok := lastTraversal.(hcl.TraverseIndex); ok {
+			editRange := hcl.Range{
+				Filename: eType.SrcRange.Filename,
+				Start:    pos,
+				End:      pos,
+			}
+			expr := &hclsyntax.LiteralValueExpr{
+				SrcRange: editRange,
+				Val:      cty.UnknownVal(cty.DynamicPseudoType),
+			}
+			return newExpression(a.pathCtx, expr, cons).CompletionAtPos(ctx, pos)
+		}
+	// If there is a prefix or valid expression within the index step,
+	// we're dealing an index expression and can defer completion for the key.
+	case *hclsyntax.IndexExpr:
+		return newExpression(a.pathCtx, eType.Key, cons).CompletionAtPos(ctx, pos)
+	}
+
+	return candidates
+}
+
+func (a Any) hoverIndexExprAtPos(ctx context.Context, pos hcl.Pos) (*lang.HoverData, bool) {
+	if eType, ok := a.expr.(*hclsyntax.IndexExpr); ok {
+		if eType.Key.Range().ContainsPos(pos) {
+			cons := schema.AnyExpression{
+				OfType: cty.String, // TODO improve type (could be int)
+			}
+			return newExpression(a.pathCtx, eType.Key, cons).HoverAtPos(ctx, pos), true
+		}
+	}
+
+	return nil, false
+}
+
+func (a Any) semanticTokensForIndexExpr(ctx context.Context) ([]lang.SemanticToken, bool) {
+	if eType, ok := a.expr.(*hclsyntax.IndexExpr); ok {
+		cons := schema.AnyExpression{
+			OfType: cty.String, // TODO improve type (could be int)
+		}
+		return newExpression(a.pathCtx, eType.Key, cons).SemanticTokens(ctx), true
+	}
+
+	return nil, false
+}