start moving statement logic into dedicated Statement class

src/Bundle.js

@@ -67,7 +67,7 @@ export default class Bundle {
 
 				if ( entryModule.exports.default ) {
 					let defaultExportName = makeLegalIdentifier( basename( this.entryPath ).slice( 0, -extname( this.entryPath ).length ) );
-					while ( entryModule.ast._scope.contains( defaultExportName ) ) {
+					while ( entryModule.scope.contains( defaultExportName ) ) {
 						defaultExportName = `_${defaultExportName}`;
 					}
 
@@ -197,7 +197,7 @@ export default class Bundle {
 				}
 			}
 
-			replaceIdentifiers( statement, source, replacements );
+			replaceIdentifiers( statement.node, source, replacements );
 
 			// add leading comments
 			if ( statement._leadingComments.length ) {

src/Module.js

@@ -2,6 +2,7 @@ import { relative } from 'path';
 import { Promise } from 'sander';
 import { parse } from 'acorn';
 import MagicString from 'magic-string';
+import Statement from './Statement';
 import analyse from './ast/analyse';
 import { has, keys } from './utils/object';
 import { sequence } from './utils/promise';
@@ -34,6 +35,10 @@ export default class Module {
 			throw err;
 		}
 
+		this.statements = this.ast.body.map( node => {
+			return new Statement( node );
+		});
+
 		this.analyse();
 	}
 
@@ -42,7 +47,7 @@ export default class Module {
 		this.imports = {};
 		this.exports = {};
 
-		this.ast.body.forEach( node => {
+		this.statements.forEach( node => {
 			let source;
 
 			// import foo from './foo';
@@ -142,7 +147,7 @@ export default class Module {
 
 		analyse( this.ast, this.code, this );
 
-		this.definedNames = this.ast._scope.names.slice();
+		this.definedNames = this.scope.names.slice(); // TODO is this used?
 
 		this.canonicalNames = {};
 
@@ -150,7 +155,7 @@ export default class Module {
 		this.definitionPromises = {};
 		this.modifications = {};
 
-		this.ast.body.forEach( statement => {
+		this.statements.forEach( statement => {
 			Object.keys( statement._defines ).forEach( name => {
 				this.definitions[ name ] = statement;
 			});
@@ -339,7 +344,7 @@ export default class Module {
 	expandAllStatements ( isEntryModule ) {
 		let allStatements = [];
 
-		return sequence( this.ast.body, statement => {
+		return sequence( this.statements, statement => {
 			// skip already-included statements
 			if ( statement._included ) return;
 

src/Statement.js

@@ -0,0 +1,10 @@
+import { keys } from './utils/object';
+
+export default class Statement {
+	constructor ( node ) {
+		// TODO remove this in favour of this.node
+		keys( node ).forEach( key => this[ key ] = node[ key ] );
+
+		this.node = node;
+	}
+}

src/ast/analyse.js

@@ -30,7 +30,7 @@ export default function analyse ( ast, magicString, module ) {
 	let previousStatement = null;
 	let commentIndex = 0;
 
-	ast.body.forEach( statement => {
+	module.statements.forEach( statement => {
 		currentTopLevelStatement = statement; // so we can attach scoping info
 
 		Object.defineProperties( statement, {
@@ -87,7 +87,7 @@ export default function analyse ( ast, magicString, module ) {
 		if ( previousStatement ) previousStatement._margin[1] = margin;
 		statement._margin[0] = margin;
 
-		walk( statement, {
+		walk( statement.node, {
 			enter ( node ) {
 				let newScope;
 
@@ -160,7 +160,7 @@ export default function analyse ( ast, magicString, module ) {
 
 	// then, we need to find which top-level dependencies this statement has,
 	// and which it potentially modifies
-	ast.body.forEach( statement => {
+	module.statements.forEach( statement => {
 		function checkForReads ( node, parent ) {
 			if ( node.type === 'Identifier' ) {
 				// disregard the `bar` in `foo.bar` - these appear as Identifier nodes
@@ -237,5 +237,5 @@ export default function analyse ( ast, magicString, module ) {
 		});
 	});
 
-	ast._scope = scope;
+	module.scope = scope;
 }