lang: ast, interfaces: Move textarea to a common package

We're going to use it everywhere. We also make it more forgiving in the
meanwhile while we're porting things over.

lang/ast/structs.go

@@ -183,7 +183,8 @@ var (
 // StmtBind is a representation of an assignment, which binds a variable to an
 // expression.
 type StmtBind struct {
-	Textarea
+	interfaces.Textarea
+
 	data *interfaces.Data
 
 	Ident string
@@ -378,7 +379,8 @@ func (obj *StmtBind) Output(map[interfaces.Func]types.Value) (*interfaces.Output
 // TODO: Consider expanding Name to have this return a list of Res's in the
 // Output function if it is a map[name]struct{}, or even a map[[]name]struct{}.
 type StmtRes struct {
-	Textarea
+	interfaces.Textarea
+
 	data *interfaces.Data
 
 	Kind     string            // kind of resource, eg: pkg, file, svc, etc...
@@ -1594,7 +1596,8 @@ type StmtResContents interface {
 // StmtResField represents a single field in the parsed resource representation.
 // This does not satisfy the Stmt interface.
 type StmtResField struct {
-	Textarea
+	interfaces.Textarea
+
 	data *interfaces.Data
 
 	Field        string
@@ -1879,7 +1882,8 @@ func (obj *StmtResField) Graph(env *interfaces.Env) (*pgraph.Graph, error) {
 // StmtResEdge represents a single edge property in the parsed resource
 // representation. This does not satisfy the Stmt interface.
 type StmtResEdge struct {
-	Textarea
+	interfaces.Textarea
+
 	data *interfaces.Data
 
 	Property     string // TODO: iota constant instead?
@@ -2129,7 +2133,8 @@ func (obj *StmtResEdge) Graph(env *interfaces.Env) (*pgraph.Graph, error) {
 // correspond to the particular meta parameter specified. This does not satisfy
 // the Stmt interface.
 type StmtResMeta struct {
-	Textarea
+	interfaces.Textarea
+
 	data *interfaces.Data
 
 	Property     string // TODO: iota constant instead?
@@ -2683,7 +2688,8 @@ func (obj *StmtResCollect) Graph(env *interfaces.Env) (*pgraph.Graph, error) {
 // names are compatible and listed. In this case of Send/Recv, only lists of
 // length two are legal.
 type StmtEdge struct {
-	Textarea
+	interfaces.Textarea
+
 	data *interfaces.Data
 
 	EdgeHalfList []*StmtEdgeHalf // represents a chain of edges
@@ -3032,7 +3038,8 @@ func (obj *StmtEdge) Output(table map[interfaces.Func]types.Value) (*interfaces.
 // is assumed that a list of strings should be expected. More mechanisms to
 // determine if the value is static may be added over time.
 type StmtEdgeHalf struct {
-	Textarea
+	interfaces.Textarea
+
 	data *interfaces.Data
 
 	Kind     string          // kind of resource, eg: pkg, file, svc, etc...
@@ -3203,7 +3210,8 @@ func (obj *StmtEdgeHalf) Graph(env *interfaces.Env) (*pgraph.Graph, error) {
 // optional, it is the else branch, although this struct allows either to be
 // optional, even if it is not commonly used.
 type StmtIf struct {
-	Textarea
+	interfaces.Textarea
+
 	data *interfaces.Data
 
 	Condition    interfaces.Expr
@@ -3569,7 +3577,8 @@ func (obj *StmtIf) Output(table map[interfaces.Func]types.Value) (*interfaces.Ou
 
 // StmtFor represents an iteration over a list. The body contains statements.
 type StmtFor struct {
-	Textarea
+	interfaces.Textarea
+
 	data  *interfaces.Data
 	scope *interfaces.Scope // store for referencing this later
 
@@ -4077,7 +4086,8 @@ func (obj *StmtFor) Output(table map[interfaces.Func]types.Value) (*interfaces.O
 
 // StmtForKV represents an iteration over a map. The body contains statements.
 type StmtForKV struct {
-	Textarea
+	interfaces.Textarea
+
 	data  *interfaces.Data
 	scope *interfaces.Scope // store for referencing this later
 
@@ -4583,7 +4593,8 @@ func (obj *StmtForKV) Output(table map[interfaces.Func]types.Value) (*interfaces
 // the bind statement's are correctly applied in this scope, and irrespective of
 // their order of definition.
 type StmtProg struct {
-	Textarea
+	interfaces.Textarea
+
 	data  *interfaces.Data
 	scope *interfaces.Scope // store for use by imports
 
@@ -6177,7 +6188,8 @@ func (obj *StmtProg) IsModuleUnsafe() error { // TODO: rename this function?
 // the supplied function in the current scope and irrespective of the order of
 // definition.
 type StmtFunc struct {
-	Textarea
+	interfaces.Textarea
+
 	data *interfaces.Data
 
 	Name string
@@ -6391,7 +6403,8 @@ func (obj *StmtFunc) Output(map[interfaces.Func]types.Value) (*interfaces.Output
 // TODO: We don't currently support defining polymorphic classes (eg: different
 // signatures for the same class name) but it might be something to consider.
 type StmtClass struct {
-	Textarea
+	interfaces.Textarea
+
 	data  *interfaces.Data
 	scope *interfaces.Scope // store for referencing this later
 
@@ -6601,7 +6614,8 @@ func (obj *StmtClass) Output(table map[interfaces.Func]types.Value) (*interfaces
 // to call a class except that it produces output instead of a value. Most of
 // the interesting logic for classes happens here or in StmtProg.
 type StmtInclude struct {
-	Textarea
+	interfaces.Textarea
+
 	data  *interfaces.Data
 	scope *interfaces.Scope
 
@@ -7099,7 +7113,8 @@ func (obj *StmtInclude) Output(table map[interfaces.Func]types.Value) (*interfac
 // file. As with any statement, it produces output, but that output is empty. To
 // benefit from its inclusion, reference the scope definitions you want.
 type StmtImport struct {
-	Textarea
+	interfaces.Textarea
+
 	data *interfaces.Data
 
 	Name  string
@@ -7208,7 +7223,7 @@ func (obj *StmtImport) Output(map[interfaces.Func]types.Value) (*interfaces.Outp
 // formatting) but so that they can exist anywhere in the code. Currently these
 // are dropped by the lexer.
 type StmtComment struct {
-	Textarea
+	interfaces.Textarea
 
 	Value string
 }
@@ -7290,7 +7305,8 @@ func (obj *StmtComment) Output(map[interfaces.Func]types.Value) (*interfaces.Out
 
 // ExprBool is a representation of a boolean.
 type ExprBool struct {
-	Textarea
+	interfaces.Textarea
+
 	data  *interfaces.Data
 	scope *interfaces.Scope // store for referencing this later
 
@@ -7443,7 +7459,8 @@ func (obj *ExprBool) Value() (types.Value, error) {
 
 // ExprStr is a representation of a string.
 type ExprStr struct {
-	Textarea
+	interfaces.Textarea
+
 	data  *interfaces.Data
 	scope *interfaces.Scope // store for referencing this later
 
@@ -7645,7 +7662,8 @@ func (obj *ExprStr) Value() (types.Value, error) {
 
 // ExprInt is a representation of an int.
 type ExprInt struct {
-	Textarea
+	interfaces.Textarea
+
 	data  *interfaces.Data
 	scope *interfaces.Scope // store for referencing this later
 
@@ -7797,7 +7815,8 @@ func (obj *ExprInt) Value() (types.Value, error) {
 
 // ExprFloat is a representation of a float.
 type ExprFloat struct {
-	Textarea
+	interfaces.Textarea
+
 	data  *interfaces.Data
 	scope *interfaces.Scope // store for referencing this later
 
@@ -7951,7 +7970,8 @@ func (obj *ExprFloat) Value() (types.Value, error) {
 
 // ExprList is a representation of a list.
 type ExprList struct {
-	Textarea
+	interfaces.Textarea
+
 	data  *interfaces.Data
 	scope *interfaces.Scope // store for referencing this later
 	typ   *types.Type
@@ -8315,7 +8335,8 @@ func (obj *ExprList) Value() (types.Value, error) {
 
 // ExprMap is a representation of a (dictionary) map.
 type ExprMap struct {
-	Textarea
+	interfaces.Textarea
+
 	data  *interfaces.Data
 	scope *interfaces.Scope // store for referencing this later
 	typ   *types.Type
@@ -8804,7 +8825,7 @@ func (obj *ExprMap) Value() (types.Value, error) {
 // ExprMapKV represents a key and value pair in a (dictionary) map. This does
 // not satisfy the Expr interface.
 type ExprMapKV struct {
-	Textarea
+	interfaces.Textarea
 
 	Key interfaces.Expr // keys can be strings, int's, etc...
 	Val interfaces.Expr
@@ -8812,7 +8833,8 @@ type ExprMapKV struct {
 
 // ExprStruct is a representation of a struct.
 type ExprStruct struct {
-	Textarea
+	interfaces.Textarea
+
 	data  *interfaces.Data
 	scope *interfaces.Scope // store for referencing this later
 	typ   *types.Type
@@ -9208,7 +9230,7 @@ func (obj *ExprStruct) Value() (types.Value, error) {
 // ExprStructField represents a name value pair in a struct field. This does not
 // satisfy the Expr interface.
 type ExprStructField struct {
-	Textarea
+	interfaces.Textarea
 
 	Name  string
 	Value interfaces.Expr
@@ -9224,7 +9246,8 @@ type ExprStructField struct {
 // 4. A pure built-in function (set Values to a singleton)
 // 5. A pure polymorphic built-in function (set Values to a list)
 type ExprFunc struct {
-	Textarea
+	interfaces.Textarea
+
 	data  *interfaces.Data
 	scope *interfaces.Scope // store for referencing this later
 	typ   *types.Type
@@ -10139,7 +10162,8 @@ func (obj *ExprFunc) Value() (types.Value, error) {
 // declaration or implementation of a new function value. This struct has an
 // analogous symmetry with ExprVar.
 type ExprCall struct {
-	Textarea
+	interfaces.Textarea
+
 	data  *interfaces.Data
 	scope *interfaces.Scope // store for referencing this later
 	typ   *types.Type
@@ -11118,7 +11142,8 @@ func (obj *ExprCall) Value() (types.Value, error) {
 // ExprVar is a representation of a variable lookup. It returns the expression
 // that that variable refers to.
 type ExprVar struct {
-	Textarea
+	interfaces.Textarea
+
 	data  *interfaces.Data
 	scope *interfaces.Scope // store for referencing this later
 	typ   *types.Type
@@ -12322,7 +12347,8 @@ func (obj *ExprSingleton) Value() (types.Value, error) {
 // returns a value. As a result, it has a type. This is different from a StmtIf,
 // which does not need to have both branches, and which does not return a value.
 type ExprIf struct {
-	Textarea
+	interfaces.Textarea
+
 	data  *interfaces.Data
 	scope *interfaces.Scope // store for referencing this later
 	typ   *types.Type