decoder: Decouple each validator into its own type

decoder/internal/validator/attribute_deprecated.go

@@ -0,0 +1,34 @@
+package validator
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/hashicorp/hcl-lang/schema"
+	"github.com/hashicorp/hcl/v2"
+	"github.com/hashicorp/hcl/v2/hclsyntax"
+)
+
+type DeprecatedAttribute struct{}
+
+func (v DeprecatedAttribute) Visit(ctx context.Context, node hclsyntax.Node, nodeSchema schema.Schema) (diags hcl.Diagnostics) {
+	attr, ok := node.(*hclsyntax.Attribute)
+	if !ok {
+		return
+	}
+
+	if nodeSchema == nil {
+		return
+	}
+	attrSchema := nodeSchema.(*schema.AttributeSchema)
+	if attrSchema.IsDeprecated {
+		diags = append(diags, &hcl.Diagnostic{
+			Severity: hcl.DiagWarning,
+			Summary:  fmt.Sprintf("%q is deprecated", attr.Name),
+			Detail:   fmt.Sprintf("Reason: %q", attrSchema.Description.Value),
+			Subject:  attr.SrcRange.Ptr(),
+		})
+	}
+
+	return
+}

decoder/internal/validator/attribute_missing_required.go

@@ -0,0 +1,44 @@
+package validator
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/hashicorp/hcl-lang/schema"
+	"github.com/hashicorp/hcl/v2"
+	"github.com/hashicorp/hcl/v2/hclsyntax"
+)
+
+type MissingRequiredAttribute struct{}
+
+func (v MissingRequiredAttribute) Visit(ctx context.Context, node hclsyntax.Node, nodeSchema schema.Schema) (diags hcl.Diagnostics) {
+	body, ok := node.(*hclsyntax.Body)
+	if !ok {
+		return
+	}
+
+	if nodeSchema == nil {
+		return
+	}
+
+	bodySchema := nodeSchema.(*schema.BodySchema)
+	if bodySchema.Attributes == nil {
+		return
+	}
+
+	for name, attr := range bodySchema.Attributes {
+		if attr.IsRequired {
+			_, ok := body.Attributes[name]
+			if !ok {
+				diags = append(diags, &hcl.Diagnostic{
+					Severity: hcl.DiagError,
+					Summary:  fmt.Sprintf("Required attribute %q not specified", name),
+					Detail:   fmt.Sprintf("An attribute named %q is required here", name),
+					Subject:  body.SrcRange.Ptr(),
+				})
+			}
+		}
+	}
+
+	return
+}

decoder/internal/validator/attribute_unexpected.go

@@ -0,0 +1,30 @@
+package validator
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/hashicorp/hcl-lang/schema"
+	"github.com/hashicorp/hcl/v2"
+	"github.com/hashicorp/hcl/v2/hclsyntax"
+)
+
+type UnexpectedAttribute struct{}
+
+func (v UnexpectedAttribute) Visit(ctx context.Context, node hclsyntax.Node, nodeSchema schema.Schema) (diags hcl.Diagnostics) {
+	attr, ok := node.(*hclsyntax.Attribute)
+	if !ok {
+		return
+	}
+
+	if nodeSchema == nil {
+		diags = append(diags, &hcl.Diagnostic{
+			Severity: hcl.DiagError,
+			Summary:  "Unexpected attribute",
+			Detail:   fmt.Sprintf("An attribute named %q is not expected here", attr.Name),
+			Subject:  attr.SrcRange.Ptr(),
+		})
+	}
+
+	return
+}

decoder/internal/validator/block_deprecated.go

@@ -0,0 +1,34 @@
+package validator
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/hashicorp/hcl-lang/schema"
+	"github.com/hashicorp/hcl/v2"
+	"github.com/hashicorp/hcl/v2/hclsyntax"
+)
+
+type DeprecatedBlock struct{}
+
+func (v DeprecatedBlock) Visit(ctx context.Context, node hclsyntax.Node, nodeSchema schema.Schema) (diags hcl.Diagnostics) {
+	block, ok := node.(*hclsyntax.Block)
+	if !ok {
+		return
+	}
+
+	if nodeSchema == nil {
+		return
+	}
+	blockSchema := nodeSchema.(*schema.BlockSchema)
+	if blockSchema.IsDeprecated {
+		diags = append(diags, &hcl.Diagnostic{
+			Severity: hcl.DiagWarning,
+			Summary:  fmt.Sprintf("%q is deprecated", block.Type),
+			Detail:   fmt.Sprintf("Reason: %q", blockSchema.Description.Value),
+			Subject:  block.TypeRange.Ptr(),
+		})
+	}
+
+	return
+}

decoder/internal/validator/block_labels_length.go

@@ -0,0 +1,48 @@
+package validator
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/hashicorp/hcl-lang/schema"
+	"github.com/hashicorp/hcl/v2"
+	"github.com/hashicorp/hcl/v2/hclsyntax"
+)
+
+type BlockLabelsLength struct{}
+
+func (v BlockLabelsLength) Visit(ctx context.Context, node hclsyntax.Node, nodeSchema schema.Schema) (diags hcl.Diagnostics) {
+	block, ok := node.(*hclsyntax.Block)
+	if !ok {
+		return
+	}
+
+	if nodeSchema == nil {
+		return
+	}
+
+	blockSchema := nodeSchema.(*schema.BlockSchema)
+
+	validLabelNum := len(blockSchema.Labels)
+	for i := range block.Labels {
+		if i >= validLabelNum {
+			diags = append(diags, &hcl.Diagnostic{
+				Severity: hcl.DiagError,
+				Summary:  fmt.Sprintf("Too many labels specified for %q", block.Type),
+				Detail:   fmt.Sprintf("Only %d label(s) are expected for %q blocks", validLabelNum, block.Type),
+				Subject:  block.LabelRanges[i].Ptr(),
+			})
+		}
+	}
+
+	if validLabelNum > len(block.Labels) {
+		diags = append(diags, &hcl.Diagnostic{
+			Severity: hcl.DiagError,
+			Summary:  fmt.Sprintf("Not enough labels specified for %q", block.Type),
+			Detail:   fmt.Sprintf("All %q blocks must have %d label(s)", block.Type, validLabelNum),
+			Subject:  block.TypeRange.Ptr(),
+		})
+	}
+
+	return
+}

decoder/internal/validator/block_max_items.go

@@ -0,0 +1,49 @@
+package validator
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/hashicorp/hcl-lang/schema"
+	"github.com/hashicorp/hcl/v2"
+	"github.com/hashicorp/hcl/v2/hclsyntax"
+)
+
+type MaxBlocks struct{}
+
+func (v MaxBlocks) Visit(ctx context.Context, node hclsyntax.Node, nodeSchema schema.Schema) (diags hcl.Diagnostics) {
+	body, ok := node.(*hclsyntax.Body)
+	if !ok {
+		return
+	}
+
+	if nodeSchema == nil {
+		return
+	}
+
+	foundBlocks := make(map[string]uint64)
+	for _, block := range body.Blocks {
+		if _, ok := foundBlocks[block.Type]; !ok {
+			foundBlocks[block.Type] = 0
+		}
+
+		foundBlocks[block.Type]++
+	}
+
+	bodySchema := nodeSchema.(*schema.BodySchema)
+	for name, blockSchema := range bodySchema.Blocks {
+		if blockSchema.MaxItems != 0 {
+			foundBlocks, ok := foundBlocks[name]
+			if ok && foundBlocks > blockSchema.MaxItems {
+				diags = append(diags, &hcl.Diagnostic{
+					Severity: hcl.DiagError,
+					Summary:  fmt.Sprintf("Too many blocks specified for %q", name),
+					Detail:   fmt.Sprintf("Only %d block(s) are expected for %q", blockSchema.MaxItems, name),
+					Subject:  node.Range().Ptr(),
+				})
+			}
+		}
+	}
+
+	return
+}

decoder/internal/validator/block_min_items.go

@@ -0,0 +1,49 @@
+package validator
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/hashicorp/hcl-lang/schema"
+	"github.com/hashicorp/hcl/v2"
+	"github.com/hashicorp/hcl/v2/hclsyntax"
+)
+
+type MinBlocks struct{}
+
+func (v MinBlocks) Visit(ctx context.Context, node hclsyntax.Node, nodeSchema schema.Schema) (diags hcl.Diagnostics) {
+	body, ok := node.(*hclsyntax.Body)
+	if !ok {
+		return
+	}
+
+	if nodeSchema == nil {
+		return
+	}
+
+	foundBlocks := make(map[string]uint64)
+	for _, block := range body.Blocks {
+		if _, ok := foundBlocks[block.Type]; !ok {
+			foundBlocks[block.Type] = 0
+		}
+
+		foundBlocks[block.Type]++
+	}
+
+	bodySchema := nodeSchema.(*schema.BodySchema)
+	for name, blockSchema := range bodySchema.Blocks {
+		if blockSchema.MinItems != 0 {
+			foundBlocks, ok := foundBlocks[name]
+			if !ok || foundBlocks < blockSchema.MinItems {
+				diags = append(diags, &hcl.Diagnostic{
+					Severity: hcl.DiagError,
+					Summary:  fmt.Sprintf("Too few blocks specified for %q", name),
+					Detail:   fmt.Sprintf("At least %d block(s) are expected for %q", blockSchema.MinItems, name),
+					Subject:  node.Range().Ptr(),
+				})
+			}
+		}
+	}
+
+	return
+}

decoder/internal/validator/block_unexpected.go

@@ -0,0 +1,29 @@
+package validator
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/hashicorp/hcl-lang/schema"
+	"github.com/hashicorp/hcl/v2"
+	"github.com/hashicorp/hcl/v2/hclsyntax"
+)
+
+type UnexpectedBlock struct{}
+
+func (v UnexpectedBlock) Visit(ctx context.Context, node hclsyntax.Node, nodeSchema schema.Schema) (diags hcl.Diagnostics) {
+	block, ok := node.(*hclsyntax.Block)
+	if !ok {
+		return
+	}
+
+	if nodeSchema == nil {
+		diags = append(diags, &hcl.Diagnostic{
+			Severity: hcl.DiagError,
+			Summary:  "Unexpected block",
+			Detail:   fmt.Sprintf("Blocks of type %q are not expected here", block.Type),
+			Subject:  block.TypeRange.Ptr(),
+		})
+	}
+	return
+}

decoder/internal/validator/validators.go

@@ -0,0 +1,16 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+package validator
+
+import (
+	"context"
+
+	"github.com/hashicorp/hcl-lang/schema"
+	"github.com/hashicorp/hcl/v2"
+	"github.com/hashicorp/hcl/v2/hclsyntax"
+)
+
+type Validator interface {
+	Visit(ctx context.Context, node hclsyntax.Node, nodeSchema schema.Schema) hcl.Diagnostics
+}