replace parser with actions/workflow-parser

vendor/github.com/actions/workflow-parser/parser/parser.go

@@ -0,0 +1,807 @@
+package parser
+
+import (
+	"fmt"
+	"io"
+	"io/ioutil"
+	"regexp"
+	"strings"
+
+	"github.com/actions/workflow-parser/model"
+	"github.com/hashicorp/hcl"
+	"github.com/hashicorp/hcl/hcl/ast"
+	hclparser "github.com/hashicorp/hcl/hcl/parser"
+	"github.com/hashicorp/hcl/hcl/token"
+	"github.com/soniakeys/graph"
+)
+
+const minVersion = 0
+const maxVersion = 0
+const maxSecrets = 100
+
+type parseState struct {
+	Version   int
+	Actions   []*model.Action
+	Workflows []*model.Workflow
+	Errors    ErrorList
+
+	posMap           map[interface{}]ast.Node
+	suppressSeverity Severity
+}
+
+// Parse parses a .workflow file and return the actions and global variables found within.
+func Parse(reader io.Reader, options ...OptionFunc) (*model.Configuration, error) {
+	// FIXME - check context for deadline?
+	b, err := ioutil.ReadAll(reader)
+	if err != nil {
+		return nil, err
+	}
+
+	root, err := hcl.ParseBytes(b)
+	if err != nil {
+		if pe, ok := err.(*hclparser.PosError); ok {
+			pos := ErrorPos{File: pe.Pos.Filename, Line: pe.Pos.Line, Column: pe.Pos.Column}
+			errors := ErrorList{newFatal(pos, pe.Err.Error())}
+			return nil, &ParserError{
+				message: pe.Err.Error(),
+				Errors:  errors,
+			}
+		}
+		return nil, err
+	}
+
+	ps := parseAndValidate(root.Node, options...)
+	if len(ps.Errors) > 0 {
+		return nil, &ParserError{
+			message:   "unable to parse and validate",
+			Errors:    ps.Errors,
+			Actions:   ps.Actions,
+			Workflows: ps.Workflows,
+		}
+	}
+
+	return &model.Configuration{
+		Actions:   ps.Actions,
+		Workflows: ps.Workflows,
+	}, nil
+}
+
+// parseAndValidate converts a HCL AST into a parseState and validates
+// high-level structure.
+// Parameters:
+//  - root - the contents of a .workflow file, as AST
+// Returns:
+//  - a parseState structure containing actions and workflow definitions
+func parseAndValidate(root ast.Node, options ...OptionFunc) *parseState {
+	ps := &parseState{
+		posMap: make(map[interface{}]ast.Node),
+	}
+
+	for _, option := range options {
+		option(ps)
+	}
+
+	ps.parseRoot(root)
+	ps.validate()
+	ps.Errors.sort()
+
+	return ps
+}
+
+func (ps *parseState) validate() {
+	ps.analyzeDependencies()
+	ps.checkCircularDependencies()
+	ps.checkActions()
+	ps.checkFlows()
+}
+
+func uniqStrings(items []string) []string {
+	seen := make(map[string]bool)
+	ret := make([]string, 0, len(items))
+	for _, item := range items {
+		if !seen[item] {
+			seen[item] = true
+			ret = append(ret, item)
+		}
+	}
+	return ret
+}
+
+// checkCircularDependencies finds loops in the action graph.
+// It emits a fatal error for each cycle it finds, in the order (top to
+// bottom, left to right) they appear in the .workflow file.
+func (ps *parseState) checkCircularDependencies() {
+	// make a map from action name to node ID, which is the index in the ps.Actions array
+	// That is, ps.Actions[actionmap[X]].Identifier == X
+	actionmap := make(map[string]graph.NI)
+	for i, action := range ps.Actions {
+		actionmap[action.Identifier] = graph.NI(i)
+	}
+
+	// make an adjacency list representation of the action dependency graph
+	adjList := make(graph.AdjacencyList, len(ps.Actions))
+	for i, action := range ps.Actions {
+		adjList[i] = make([]graph.NI, 0, len(action.Needs))
+		for _, depName := range action.Needs {
+			if depIdx, ok := actionmap[depName]; ok {
+				adjList[i] = append(adjList[i], depIdx)
+			}
+		}
+	}
+
+	// find cycles, and print a fatal error for each one
+	g := graph.Directed{AdjacencyList: adjList}
+	g.Cycles(func(cycle []graph.NI) bool {
+		node := ps.posMap[&ps.Actions[cycle[len(cycle)-1]].Needs]
+		ps.addFatal(node, "Circular dependency on `%s'", ps.Actions[cycle[0]].Identifier)
+		return true
+	})
+}
+
+// checkActions returns error if any actions are syntactically correct but
+// have structural errors
+func (ps *parseState) checkActions() {
+	secrets := make(map[string]bool)
+	for _, t := range ps.Actions {
+		// Ensure the Action has a `uses` attribute
+		if t.Uses == nil {
+			ps.addError(ps.posMap[t], "Action `%s' must have a `uses' attribute", t.Identifier)
+			// continue, checking other actions
+		}
+
+		// Ensure there aren't too many secrets
+		for _, str := range t.Secrets {
+			if !secrets[str] {
+				secrets[str] = true
+				if len(secrets) == maxSecrets+1 {
+					ps.addError(ps.posMap[&t.Secrets], "All actions combined must not have more than %d unique secrets", maxSecrets)
+				}
+			}
+		}
+
+		// Ensure that no environment variable or secret begins with
+		// "GITHUB_", unless it's "GITHUB_TOKEN".
+		// Also ensure that all environment variable names come from the legal
+		// form for environment variable names.
+		// Finally, ensure that the same key name isn't used more than once
+		// between env and secrets, combined.
+		for k := range t.Env {
+			ps.checkEnvironmentVariable(k, ps.posMap[&t.Env])
+		}
+		secretVars := make(map[string]bool)
+		for _, k := range t.Secrets {
+			ps.checkEnvironmentVariable(k, ps.posMap[&t.Secrets])
+			if _, found := t.Env[k]; found {
+				ps.addError(ps.posMap[&t.Secrets], "Secret `%s' conflicts with an environment variable with the same name", k)
+			}
+			if secretVars[k] {
+				ps.addWarning(ps.posMap[&t.Secrets], "Secret `%s' redefined", k)
+			}
+			secretVars[k] = true
+		}
+	}
+}
+
+var envVarChecker = regexp.MustCompile(`\A[A-Za-z_][A-Za-z_0-9]*\z`)
+
+func (ps *parseState) checkEnvironmentVariable(key string, node ast.Node) {
+	if key != "GITHUB_TOKEN" && strings.HasPrefix(key, "GITHUB_") {
+		ps.addWarning(node, "Environment variables and secrets beginning with `GITHUB_' are reserved")
+	}
+	if !envVarChecker.MatchString(key) {
+		ps.addWarning(node, "Environment variables and secrets must contain only A-Z, a-z, 0-9, and _ characters, got `%s'", key)
+	}
+}
+
+// checkFlows appends an error if any workflows are syntactically correct but
+// have structural errors
+func (ps *parseState) checkFlows() {
+	actionmap := makeActionMap(ps.Actions)
+	for _, f := range ps.Workflows {
+		// make sure there's an `on` attribute
+		if f.On == "" {
+			ps.addError(ps.posMap[f], "Workflow `%s' must have an `on' attribute", f.Identifier)
+			// continue, checking other workflows
+		} else if !model.IsAllowedEventType(f.On) {
+			ps.addError(ps.posMap[&f.On], "Workflow `%s' has unknown `on' value `%s'", f.Identifier, f.On)
+			// continue, checking other workflows
+		}
+
+		// make sure that the actions that are resolved all exist
+		for _, actionID := range f.Resolves {
+			_, ok := actionmap[actionID]
+			if !ok {
+				ps.addError(ps.posMap[&f.Resolves], "Workflow `%s' resolves unknown action `%s'", f.Identifier, actionID)
+				// continue, checking other workflows
+			}
+		}
+	}
+}
+
+func makeActionMap(actions []*model.Action) map[string]*model.Action {
+	actionmap := make(map[string]*model.Action)
+	for _, action := range actions {
+		actionmap[action.Identifier] = action
+	}
+	return actionmap
+}
+
+// Fill in Action dependencies for all actions based on explicit dependencies
+// declarations.
+//
+// ps.Actions is an array of Action objects, as parsed.  The Action objects in
+// this array are mutated, by setting Action.dependencies for each.
+func (ps *parseState) analyzeDependencies() {
+	actionmap := makeActionMap(ps.Actions)
+	for _, action := range ps.Actions {
+		// analyze explicit dependencies for each "needs" keyword
+		ps.analyzeNeeds(action, actionmap)
+	}
+
+	// uniq all the dependencies lists
+	for _, action := range ps.Actions {
+		if len(action.Needs) >= 2 {
+			action.Needs = uniqStrings(action.Needs)
+		}
+	}
+}
+
+func (ps *parseState) analyzeNeeds(action *model.Action, actionmap map[string]*model.Action) {
+	for _, need := range action.Needs {
+		_, ok := actionmap[need]
+		if !ok {
+			ps.addError(ps.posMap[&action.Needs], "Action `%s' needs nonexistent action `%s'", action.Identifier, need)
+			// continue, checking other actions
+		}
+	}
+}
+
+// literalToStringMap converts a object value from the AST to a
+// map[string]string.  For example, the HCL `{ a="b" c="d" }` becomes the
+// Go expression map[string]string{ "a": "b", "c": "d" }.
+// If the value doesn't adhere to that format -- e.g.,
+// if it's not an object, or it has non-assignment attributes, or if any
+// of its values are anything other than a string, the function appends an
+// appropriate error.
+func (ps *parseState) literalToStringMap(node ast.Node) map[string]string {
+	obj, ok := node.(*ast.ObjectType)
+
+	if !ok {
+		ps.addError(node, "Expected object, got %s", typename(node))
+		return nil
+	}
+
+	ps.checkAssignmentsOnly(obj.List, "")
+
+	ret := make(map[string]string)
+	for _, item := range obj.List.Items {
+		if !isAssignment(item) {
+			continue
+		}
+		str, ok := ps.literalToString(item.Val)
+		if ok {
+			key := ps.identString(item.Keys[0].Token)
+			if key != "" {
+				if _, found := ret[key]; found {
+					ps.addWarning(node, "Environment variable `%s' redefined", key)
+				}
+				ret[key] = str
+			}
+		}
+	}
+
+	return ret
+}
+
+func (ps *parseState) identString(t token.Token) string {
+	switch t.Type {
+	case token.STRING:
+		return t.Value().(string)
+	case token.IDENT:
+		return t.Text
+	default:
+		ps.addErrorFromToken(t,
+			"Each identifier should be a string, got %s",
+			strings.ToLower(t.Type.String()))
+		return ""
+	}
+}
+
+// literalToStringArray converts a list value from the AST to a []string.
+// For example, the HCL `[ "a", "b", "c" ]` becomes the Go expression
+// []string{ "a", "b", "c" }.
+// If the value doesn't adhere to that format -- it's not a list, or it
+// contains anything other than strings, the function appends an
+// appropriate error.
+// If promoteScalars is true, then values that are scalar strings are
+// promoted to a single-entry string array.  E.g., "foo" becomes the Go
+// expression []string{ "foo" }.
+func (ps *parseState) literalToStringArray(node ast.Node, promoteScalars bool) ([]string, bool) {
+	literal, ok := node.(*ast.LiteralType)
+	if ok {
+		if promoteScalars && literal.Token.Type == token.STRING {
+			return []string{literal.Token.Value().(string)}, true
+		}
+		ps.addError(node, "Expected list, got %s", typename(node))
+		return nil, false
+	}
+
+	list, ok := node.(*ast.ListType)
+	if !ok {
+		ps.addError(node, "Expected list, got %s", typename(node))
+		return nil, false
+	}
+
+	ret := make([]string, 0, len(list.List))
+	for _, literal := range list.List {
+		str, ok := ps.literalToString(literal)
+		if ok {
+			ret = append(ret, str)
+		}
+	}
+
+	return ret, true
+}
+
+// literalToString converts a literal value from the AST into a string.
+// If the value isn't a scalar or isn't a string, the function appends an
+// appropriate error and returns "", false.
+func (ps *parseState) literalToString(node ast.Node) (string, bool) {
+	val := ps.literalCast(node, token.STRING)
+	if val == nil {
+		return "", false
+	}
+	return val.(string), true
+}
+
+// literalToInt converts a literal value from the AST into an int64.
+// Supported number formats are: 123, 0x123, and 0123.
+// Exponents (1e6) and floats (123.456) generate errors.
+// If the value isn't a scalar or isn't a number, the function appends an
+// appropriate error and returns 0, false.
+func (ps *parseState) literalToInt(node ast.Node) (int64, bool) {
+	val := ps.literalCast(node, token.NUMBER)
+	if val == nil {
+		return 0, false
+	}
+	return val.(int64), true
+}
+
+func (ps *parseState) literalCast(node ast.Node, t token.Type) interface{} {
+	literal, ok := node.(*ast.LiteralType)
+	if !ok {
+		ps.addError(node, "Expected %s, got %s", strings.ToLower(t.String()), typename(node))
+		return nil
+	}
+
+	if literal.Token.Type != t {
+		ps.addError(node, "Expected %s, got %s", strings.ToLower(t.String()), typename(node))
+		return nil
+	}
+
+	return literal.Token.Value()
+}
+
+// parseRoot parses the root of the AST, filling in ps.Version, ps.Actions,
+// and ps.Workflows.
+func (ps *parseState) parseRoot(node ast.Node) {
+	objectList, ok := node.(*ast.ObjectList)
+	if !ok {
+		// It should be impossible for HCL to return anything other than an
+		// ObjectList as the root node.  This error should never happen.
+		ps.addError(node, "Internal error: root node must be an ObjectList")
+		return
+	}
+
+	ps.Actions = make([]*model.Action, 0, len(objectList.Items))
+	ps.Workflows = make([]*model.Workflow, 0, len(objectList.Items))
+	identifiers := make(map[string]bool)
+	for idx, item := range objectList.Items {
+		if item.Assign.IsValid() {
+			ps.parseVersion(idx, item)
+			continue
+		}
+		ps.parseBlock(item, identifiers)
+	}
+}
+
+// parseBlock parses a single, top-level "action" or "workflow" block,
+// appending it to ps.Actions or ps.Workflows as appropriate.
+func (ps *parseState) parseBlock(item *ast.ObjectItem, identifiers map[string]bool) {
+	if len(item.Keys) != 2 {
+		ps.addError(item, "Invalid toplevel declaration")
+		return
+	}
+
+	cmd := ps.identString(item.Keys[0].Token)
+	var id string
+
+	switch cmd {
+	case "action":
+		action := ps.actionifyItem(item)
+		if action != nil {
+			id = action.Identifier
+			ps.Actions = append(ps.Actions, action)
+		}
+	case "workflow":
+		workflow := ps.workflowifyItem(item)
+		if workflow != nil {
+			id = workflow.Identifier
+			ps.Workflows = append(ps.Workflows, workflow)
+		}
+	default:
+		ps.addError(item, "Invalid toplevel keyword, `%s'", cmd)
+		return
+	}
+
+	if identifiers[id] {
+		ps.addError(item, "Identifier `%s' redefined", id)
+	}
+
+	identifiers[id] = true
+}
+
+// parseVersion parses a top-level `version=N` statement, filling in
+// ps.Version.
+func (ps *parseState) parseVersion(idx int, item *ast.ObjectItem) {
+	if len(item.Keys) != 1 || ps.identString(item.Keys[0].Token) != "version" {
+		// not a valid `version` declaration
+		ps.addError(item.Val, "Toplevel declarations cannot be assignments")
+		return
+	}
+	if idx != 0 {
+		ps.addError(item.Val, "`version` must be the first declaration")
+		return
+	}
+	version, ok := ps.literalToInt(item.Val)
+	if !ok {
+		return
+	}
+	if version < minVersion || version > maxVersion {
+		ps.addError(item.Val, "`version = %d` is not supported", version)
+		return
+	}
+	ps.Version = int(version)
+}
+
+// parseIdentifier parses the double-quoted identifier (name) for a
+// "workflow" or "action" block.
+func (ps *parseState) parseIdentifier(key *ast.ObjectKey) string {
+	id := key.Token.Text
+	if len(id) < 3 || id[0] != '"' || id[len(id)-1] != '"' {
+		ps.addError(key, "Invalid format for identifier `%s'", id)
+		return ""
+	}
+	return id[1 : len(id)-1]
+}
+
+// parseRequiredString parses a string value, setting its value into the
+// out-parameter `value` and returning true if successful.
+func (ps *parseState) parseRequiredString(value *string, val ast.Node, nodeType, name, id string) bool {
+	if *value != "" {
+		ps.addWarning(val, "`%s' redefined in %s `%s'", name, nodeType, id)
+		// continue, allowing the redefinition
+	}
+
+	newVal, ok := ps.literalToString(val)
+	if !ok {
+		ps.addError(val, "Invalid format for `%s' in %s `%s', expected string", name, nodeType, id)
+		return false
+	}
+
+	if newVal == "" {
+		ps.addError(val, "`%s' value in %s `%s' cannot be blank", name, nodeType, id)
+		return false
+	}
+
+	*value = newVal
+	return true
+}
+
+// parseBlockPreamble parses the beginning of a "workflow" or "action"
+// block.
+func (ps *parseState) parseBlockPreamble(item *ast.ObjectItem, nodeType string) (string, *ast.ObjectType) {
+	id := ps.parseIdentifier(item.Keys[1])
+	if id == "" {
+		return "", nil
+	}
+
+	node := item.Val
+	obj, ok := node.(*ast.ObjectType)
+	if !ok {
+		ps.addError(node, "Each %s must have an { ...  } block", nodeType)
+		return "", nil
+	}
+
+	ps.checkAssignmentsOnly(obj.List, id)
+
+	return id, obj
+}
+
+// actionifyItem converts an AST block to an Action object.
+func (ps *parseState) actionifyItem(item *ast.ObjectItem) *model.Action {
+	id, obj := ps.parseBlockPreamble(item, "action")
+	if obj == nil {
+		return nil
+	}
+
+	action := &model.Action{
+		Identifier: id,
+	}
+	ps.posMap[action] = item
+
+	for _, item := range obj.List.Items {
+		ps.parseActionAttribute(ps.identString(item.Keys[0].Token), action, item.Val)
+	}
+
+	return action
+}
+
+// parseActionAttribute parses a single key-value pair from an "action"
+// block.  This function rejects any unknown keys and enforces formatting
+// requirements on all values.
+// It also has higher-than-normal cyclomatic complexity, so we ask the
+// gocyclo linter to ignore it.
+// nolint: gocyclo
+func (ps *parseState) parseActionAttribute(name string, action *model.Action, val ast.Node) {
+	switch name {
+	case "uses":
+		ps.parseUses(action, val)
+	case "needs":
+		needs, ok := ps.literalToStringArray(val, true)
+		if ok {
+			action.Needs = needs
+			ps.posMap[&action.Needs] = val
+		}
+	case "runs":
+		ps.parseCommand(action, &action.Runs, name, val, false)
+	case "args":
+		ps.parseCommand(action, &action.Args, name, val, true)
+	case "env":
+		env := ps.literalToStringMap(val)
+		if env != nil {
+			action.Env = env
+		}
+		ps.posMap[&action.Env] = val
+	case "secrets":
+		secrets, ok := ps.literalToStringArray(val, false)
+		if ok {
+			action.Secrets = secrets
+			ps.posMap[&action.Secrets] = val
+		}
+	default:
+		ps.addWarning(val, "Unknown action attribute `%s'", name)
+	}
+}
+
+// parseUses sets the action.Uses value based on the contents of the AST
+// node.  This function enforces formatting requirements on the value.
+func (ps *parseState) parseUses(action *model.Action, node ast.Node) {
+	if action.Uses != nil {
+		ps.addWarning(node, "`uses' redefined in action `%s'", action.Identifier)
+		// continue, allowing the redefinition
+	}
+	strVal, ok := ps.literalToString(node)
+	if !ok {
+		return
+	}
+
+	if strVal == "" {
+		action.Uses = &model.UsesInvalid{}
+		ps.addError(node, "`uses' value in action `%s' cannot be blank", action.Identifier)
+		return
+	}
+	if strings.HasPrefix(strVal, "./") {
+		action.Uses = &model.UsesPath{Path: strings.TrimPrefix(strVal, "./")}
+		return
+	}
+
+	if strings.HasPrefix(strVal, "docker://") {
+		action.Uses = &model.UsesDockerImage{Image: strings.TrimPrefix(strVal, "docker://")}
+		return
+	}
+
+	tok := strings.Split(strVal, "@")
+	if len(tok) != 2 {
+		action.Uses = &model.UsesInvalid{Raw: strVal}
+		ps.addError(node, "The `uses' attribute must be a path, a Docker image, or owner/repo@ref")
+		return
+	}
+	ref := tok[1]
+	tok = strings.SplitN(tok[0], "/", 3)
+	if len(tok) < 2 {
+		action.Uses = &model.UsesInvalid{Raw: strVal}
+		ps.addError(node, "The `uses' attribute must be a path, a Docker image, or owner/repo@ref")
+		return
+	}
+	usesRepo := &model.UsesRepository{Repository: tok[0] + "/" + tok[1], Ref: ref}
+	action.Uses = usesRepo
+	if len(tok) == 3 {
+		usesRepo.Path = tok[2]
+	}
+}
+
+// parseUses sets the action.Runs or action.Command value based on the
+// contents of the AST node.  This function enforces formatting
+// requirements on the value.
+func (ps *parseState) parseCommand(action *model.Action, dest *model.ActionCommand, name string, node ast.Node, allowBlank bool) {
+	if len(dest.Parsed) > 0 {
+		ps.addWarning(node, "`%s' redefined in action `%s'", name, action.Identifier)
+		// continue, allowing the redefinition
+	}
+
+	// Is it a list?
+	if _, ok := node.(*ast.ListType); ok {
+		if parsed, ok := ps.literalToStringArray(node, false); ok {
+			dest.Parsed = parsed
+		}
+		return
+	}
+
+	// If not, parse a whitespace-separated string into a list.
+	var raw string
+	var ok bool
+	if raw, ok = ps.literalToString(node); !ok {
+		ps.addError(node, "The `%s' attribute must be a string or a list", name)
+		return
+	}
+	if raw == "" && !allowBlank {
+		ps.addError(node, "`%s' value in action `%s' cannot be blank", name, action.Identifier)
+		return
+	}
+	dest.Raw = raw
+	dest.Parsed = strings.Fields(raw)
+}
+
+func typename(val interface{}) string {
+	switch cast := val.(type) {
+	case *ast.ListType:
+		return "list"
+	case *ast.LiteralType:
+		return strings.ToLower(cast.Token.Type.String())
+	case *ast.ObjectType:
+		return "object"
+	default:
+		return fmt.Sprintf("%T", val)
+	}
+}
+
+// workflowifyItem converts an AST block to a Workflow object.
+func (ps *parseState) workflowifyItem(item *ast.ObjectItem) *model.Workflow {
+	id, obj := ps.parseBlockPreamble(item, "workflow")
+	if obj == nil {
+		return nil
+	}
+
+	var ok bool
+	workflow := &model.Workflow{Identifier: id}
+	for _, item := range obj.List.Items {
+		name := ps.identString(item.Keys[0].Token)
+
+		switch name {
+		case "on":
+			ok = ps.parseRequiredString(&workflow.On, item.Val, "workflow", name, id)
+			if ok {
+				ps.posMap[&workflow.On] = item
+			}
+		case "resolves":
+			if workflow.Resolves != nil {
+				ps.addWarning(item.Val, "`resolves' redefined in workflow `%s'", id)
+				// continue, allowing the redefinition
+			}
+			workflow.Resolves, ok = ps.literalToStringArray(item.Val, true)
+			ps.posMap[&workflow.Resolves] = item
+			if !ok {
+				ps.addError(item.Val, "Invalid format for `resolves' in workflow `%s', expected list of strings", id)
+				// continue, allowing workflow with no `resolves`
+			}
+		default:
+			ps.addWarning(item.Val, "Unknown workflow attribute `%s'", name)
+			// continue, treat as no-op
+		}
+	}
+
+	ps.posMap[workflow] = item
+	return workflow
+}
+
+func isAssignment(item *ast.ObjectItem) bool {
+	return len(item.Keys) == 1 && item.Assign.IsValid()
+}
+
+// checkAssignmentsOnly ensures that all elements in the object are "key =
+// value" pairs.
+func (ps *parseState) checkAssignmentsOnly(objectList *ast.ObjectList, actionID string) {
+	for _, item := range objectList.Items {
+		if !isAssignment(item) {
+			var desc string
+			if actionID == "" {
+				desc = "the object"
+			} else {
+				desc = fmt.Sprintf("action `%s'", actionID)
+			}
+			ps.addErrorFromObjectItem(item, "Each attribute of %s must be an assignment", desc)
+			continue
+		}
+
+		child, ok := item.Val.(*ast.ObjectType)
+		if ok {
+			ps.checkAssignmentsOnly(child.List, actionID)
+		}
+	}
+}
+
+func (ps *parseState) addWarning(node ast.Node, format string, a ...interface{}) {
+	if ps.suppressSeverity < WARNING {
+		ps.Errors = append(ps.Errors, newWarning(posFromNode(node), format, a...))
+	}
+}
+
+func (ps *parseState) addError(node ast.Node, format string, a ...interface{}) {
+	if ps.suppressSeverity < ERROR {
+		ps.Errors = append(ps.Errors, newError(posFromNode(node), format, a...))
+	}
+}
+
+func (ps *parseState) addErrorFromToken(t token.Token, format string, a ...interface{}) {
+	if ps.suppressSeverity < ERROR {
+		ps.Errors = append(ps.Errors, newError(posFromToken(t), format, a...))
+	}
+}
+
+func (ps *parseState) addErrorFromObjectItem(objectItem *ast.ObjectItem, format string, a ...interface{}) {
+	if ps.suppressSeverity < ERROR {
+		ps.Errors = append(ps.Errors, newError(posFromObjectItem(objectItem), format, a...))
+	}
+}
+
+func (ps *parseState) addFatal(node ast.Node, format string, a ...interface{}) {
+	if ps.suppressSeverity < FATAL {
+		ps.Errors = append(ps.Errors, newFatal(posFromNode(node), format, a...))
+	}
+}
+
+// posFromNode returns an ErrorPos (file, line, and column) from an AST
+// node, so we can report specific locations for each parse error.
+func posFromNode(node ast.Node) ErrorPos {
+	var pos *token.Pos
+	switch cast := node.(type) {
+	case *ast.ObjectList:
+		if len(cast.Items) > 0 {
+			if len(cast.Items[0].Keys) > 0 {
+				pos = &cast.Items[0].Keys[0].Token.Pos
+			}
+		}
+	case *ast.ObjectItem:
+		return posFromNode(cast.Val)
+	case *ast.ObjectType:
+		pos = &cast.Lbrace
+	case *ast.LiteralType:
+		pos = &cast.Token.Pos
+	case *ast.ListType:
+		pos = &cast.Lbrack
+	case *ast.ObjectKey:
+		pos = &cast.Token.Pos
+	}
+
+	if pos == nil {
+		return ErrorPos{}
+	}
+	return ErrorPos{File: pos.Filename, Line: pos.Line, Column: pos.Column}
+}
+
+// posFromObjectItem returns an ErrorPos from an ObjectItem.  This is for
+// cases where posFromNode(item) would fail because the item has no Val
+// set.
+func posFromObjectItem(item *ast.ObjectItem) ErrorPos {
+	if len(item.Keys) > 0 {
+		return posFromNode(item.Keys[0])
+	}
+	return ErrorPos{}
+}
+
+// posFromToken returns an ErrorPos from a Token.  We can't use
+// posFromNode here because Tokens aren't Nodes.
+func posFromToken(token token.Token) ErrorPos {
+	return ErrorPos{File: token.Pos.Filename, Line: token.Pos.Line, Column: token.Pos.Column}
+}