diff --git a/gulpfile.js b/gulpfile.js
index d0d42e9..496fe67 100644
--- a/gulpfile.js
+++ b/gulpfile.js
@@ -66,7 +66,7 @@ task( "benchmark", cb => {
 // Generate the grammar parser.
 task( "build:parser", cb => {
 
-    node( "bin/peg src/grammar.pegjs -o lib/parser/grammar.js -c src/pegjs.config.js", cb );
+    node( "bin/peg src/parser.pegjs -o lib/parser.js -c src/pegjs.config.js", cb );
 
 } );
 
diff --git a/lib/parser/ast.js b/lib/ast/Grammar.js
similarity index 90%
rename from lib/parser/ast.js
rename to lib/ast/Grammar.js
index 917a511..9000030 100644
--- a/lib/parser/ast.js
+++ b/lib/ast/Grammar.js
@@ -1,20 +1,9 @@
 "use strict";
 
-const visitor = require( "../compiler/visitor" );
+const Node = require( "./Node" );
+const visitor = require( "./visitor" );
 const util = require( "../util" );
 
-class Node {
-
-    constructor( type, location ) {
-
-        this.type = type;
-        this.location = location;
-
-    }
-
-}
-exports.Node = Node;
-
 class Grammar extends Node {
 
     // Creates a new AST
@@ -57,7 +46,8 @@ class Grammar extends Node {
     }
 
 }
-exports.Grammar = Grammar;
+
+module.exports = Grammar;
 
 /* ***************************** @private ***************************** */
 
diff --git a/lib/ast/Node.js b/lib/ast/Node.js
new file mode 100644
index 0000000..3087813
--- /dev/null
+++ b/lib/ast/Node.js
@@ -0,0 +1,14 @@
+"use strict";
+
+class Node {
+
+    constructor( type, location ) {
+
+        this.type = type;
+        this.location = location;
+
+    }
+
+}
+
+module.exports = Node;
diff --git a/lib/ast/index.js b/lib/ast/index.js
new file mode 100644
index 0000000..4ac1ebb
--- /dev/null
+++ b/lib/ast/index.js
@@ -0,0 +1,5 @@
+"use strict";
+
+exports.visitor = require( "./visitor" );
+exports.Node = require( "./Node" );
+exports.Grammar = require( "./Grammar" );
diff --git a/lib/compiler/visitor.js b/lib/ast/visitor.js
similarity index 83%
rename from lib/compiler/visitor.js
rename to lib/ast/visitor.js
index 18e8718..198b5e1 100644
--- a/lib/compiler/visitor.js
+++ b/lib/ast/visitor.js
@@ -10,32 +10,34 @@ class ASTVisitor {
     visit( node ) {
 
         // istanbul ignore next
-        if ( ! node ) throw new Error( "Visitor function called with no or `null` node" );
+        if ( ! node ) throw new Error( "Visitor function called with no arguments or a `falsy` node" );
 
-        const func = this[ node.type ];
+        const fn = this[ node.type ];
 
         // istanbul ignore next
-        if ( ! func ) throw new Error( "Visitor function for node type '" + node.type + " not defined" );
+        if ( ! fn ) throw new Error( `Visitor function for node type "${ node.type }" not defined` );
 
-        const args = __slice.call( arguments, 0 );
-
-        return func.apply( this, args );
+        return fn.apply( this, arguments );
 
     }
 
+}
+
+module.exports = {
+
+    ASTVisitor,
+
     // Simple AST node visitor builder for PEG.js
-    static build( functions ) {
+    build( functions ) {
 
         let visitor = new ASTVisitor();
         util.extend( visitor, functions );
         visitor = util.enforceFastProperties( visitor );
         return visitor.visit.bind( visitor );
 
-    }
+    },
 
-}
-ASTVisitor.ASTVisitor = ASTVisitor;
-module.exports = ASTVisitor;
+};
 
 // Helper's to create visitor's for use with the ASTVisitor class
 const on = ASTVisitor.for = {
@@ -99,17 +101,19 @@ const DEFAULT_FUNCTIONS = {
 
     grammar( node ) {
 
-        const extraArgs = __slice.call( arguments, 1 );
+        const args = [ void 0 ].concat( __slice.call( arguments, 1 ) );
 
         if ( node.initializer ) {
 
-            this.visit.apply( this, [ node.initializer ].concat( extraArgs ) );
+            args[ 0 ] = node.initializer;
+            this.visit.apply( this, args );
 
         }
 
         node.rules.forEach( rule => {
 
-            this.visit.apply( this, [ rule ].concat( extraArgs ) );
+            args[ 0 ] = rule;
+            this.visit.apply( this, args );
 
         } );
 
diff --git a/lib/compiler/index.js b/lib/compiler/index.js
index fe5f913..c0515dc 100644
--- a/lib/compiler/index.js
+++ b/lib/compiler/index.js
@@ -10,7 +10,6 @@ const reportInfiniteRecursion = require( "./passes/report-infinite-recursion" );
 const reportInfiniteRepetition = require( "./passes/report-infinite-repetition" );
 const reportUndefinedRules = require( "./passes/report-undefined-rules" );
 const inferenceMatchResult = require( "./passes/inference-match-result" );
-const visitor = require( "./visitor" );
 const util = require( "../util" );
 
 function processOptions( options, defaults ) {
@@ -25,9 +24,6 @@ function processOptions( options, defaults ) {
 }
 
 const compiler = {
-    // AST node visitor builder. Useful mainly for plugins which manipulate the
-    // AST.
-    visitor: visitor,
 
     // Compiler passes.
     //
@@ -96,6 +92,7 @@ const compiler = {
         }
 
     }
+
 };
 
 module.exports = compiler;
diff --git a/lib/compiler/passes/calc-report-failures.js b/lib/compiler/passes/calc-report-failures.js
index 1bc2ce1..70d3676 100644
--- a/lib/compiler/passes/calc-report-failures.js
+++ b/lib/compiler/passes/calc-report-failures.js
@@ -1,6 +1,6 @@
 "use strict";
 
-const visitor = require( "../visitor" );
+const visitor = require( "../../ast" ).visitor;
 
 // Determines if rule always used in disabled report failure context,
 // that means, that any failures, reported within it, are never will be
diff --git a/lib/compiler/passes/generate-bytecode.js b/lib/compiler/passes/generate-bytecode.js
index f0bee29..2e679fe 100644
--- a/lib/compiler/passes/generate-bytecode.js
+++ b/lib/compiler/passes/generate-bytecode.js
@@ -1,7 +1,7 @@
 "use strict";
 
 const op = require( "../opcodes" );
-const visitor = require( "../visitor" );
+const visitor = require( "../../ast" ).visitor;
 const util = require( "../../util" );
 
 // Generates bytecode.
diff --git a/lib/compiler/passes/inference-match-result.js b/lib/compiler/passes/inference-match-result.js
index d834951..8aed1d4 100644
--- a/lib/compiler/passes/inference-match-result.js
+++ b/lib/compiler/passes/inference-match-result.js
@@ -1,6 +1,6 @@
 "use strict";
 
-const visitor      = require( "../visitor" );
+const visitor = require( "../../ast" ).visitor;
 const GrammarError = require( "../../grammar-error" );
 
 // Inference match result of the rule. Can be:
diff --git a/lib/compiler/passes/remove-proxy-rules.js b/lib/compiler/passes/remove-proxy-rules.js
index a452e0e..db32cc5 100644
--- a/lib/compiler/passes/remove-proxy-rules.js
+++ b/lib/compiler/passes/remove-proxy-rules.js
@@ -1,6 +1,6 @@
 "use strict";
 
-const visitor = require( "../visitor" );
+const visitor = require( "../../ast" ).visitor;
 
 // Removes proxy rules -- that is, rules that only delegate to other rule.
 function removeProxyRules( ast, options ) {
diff --git a/lib/compiler/passes/report-duplicate-labels.js b/lib/compiler/passes/report-duplicate-labels.js
index 35746e3..28564fc 100644
--- a/lib/compiler/passes/report-duplicate-labels.js
+++ b/lib/compiler/passes/report-duplicate-labels.js
@@ -1,7 +1,7 @@
 "use strict";
 
 const GrammarError = require( "../../grammar-error" );
-const visitor = require( "../visitor" );
+const visitor = require( "../../ast" ).visitor;
 const util = require( "../../util" );
 const __hasOwnProperty = Object.prototype.hasOwnProperty;
 
diff --git a/lib/compiler/passes/report-duplicate-rules.js b/lib/compiler/passes/report-duplicate-rules.js
index b1fb3d0..287554b 100644
--- a/lib/compiler/passes/report-duplicate-rules.js
+++ b/lib/compiler/passes/report-duplicate-rules.js
@@ -1,7 +1,7 @@
 "use strict";
 
 const GrammarError = require( "../../grammar-error" );
-const visitor = require( "../visitor" );
+const visitor = require( "../../ast" ).visitor;
 const __hasOwnProperty = Object.prototype.hasOwnProperty;
 
 // Checks that each rule is defined only once.
diff --git a/lib/compiler/passes/report-infinite-recursion.js b/lib/compiler/passes/report-infinite-recursion.js
index 9118878..def253f 100644
--- a/lib/compiler/passes/report-infinite-recursion.js
+++ b/lib/compiler/passes/report-infinite-recursion.js
@@ -1,7 +1,7 @@
 "use strict";
 
 const GrammarError = require( "../../grammar-error" );
-const visitor = require( "../visitor" );
+const visitor = require( "../../ast" ).visitor;
 
 // Reports left recursion in the grammar, which prevents infinite recursion in
 // the generated parser.
diff --git a/lib/compiler/passes/report-infinite-repetition.js b/lib/compiler/passes/report-infinite-repetition.js
index f7e7b95..72d9dc9 100644
--- a/lib/compiler/passes/report-infinite-repetition.js
+++ b/lib/compiler/passes/report-infinite-repetition.js
@@ -1,7 +1,7 @@
 "use strict";
 
 const GrammarError = require( "../../grammar-error" );
-const visitor = require( "../visitor" );
+const visitor = require( "../../ast" ).visitor;
 
 // Reports expressions that don't consume any input inside |*| or |+| in the
 // grammar, which prevents infinite loops in the generated parser.
diff --git a/lib/compiler/passes/report-undefined-rules.js b/lib/compiler/passes/report-undefined-rules.js
index 4e5796e..ea8ef24 100644
--- a/lib/compiler/passes/report-undefined-rules.js
+++ b/lib/compiler/passes/report-undefined-rules.js
@@ -1,7 +1,7 @@
 "use strict";
 
 const GrammarError = require( "../../grammar-error" );
-const visitor = require( "../visitor" );
+const visitor = require( "../../ast" ).visitor;
 
 // Checks that all referenced rules exist.
 function reportUndefinedRules( ast, options ) {
diff --git a/lib/parser/grammar.js b/lib/parser.js
similarity index 99%
rename from lib/parser/grammar.js
rename to lib/parser.js
index b2f2060..33a62d1 100644
--- a/lib/parser/grammar.js
+++ b/lib/parser.js
@@ -5,7 +5,7 @@
 "use strict";
 
 var ast = require("./ast");
-var util = require("../util");
+var util = require("./util");
 
 function peg$subclass(child, parent) {
   function C() { this.constructor = child; }
diff --git a/lib/parser/index.js b/lib/parser/index.js
deleted file mode 100644
index a79660f..0000000
--- a/lib/parser/index.js
+++ /dev/null
@@ -1,9 +0,0 @@
-"use strict";
-
-const ast = require( "./ast" );
-const parser = require( "./grammar" );
-
-parser.Grammar = ast.Grammar;
-parser.Node = ast.Node;
-
-module.exports = parser;
diff --git a/lib/peg.js b/lib/peg.js
index 7304ef1..432f9a0 100644
--- a/lib/peg.js
+++ b/lib/peg.js
@@ -1,6 +1,7 @@
 "use strict";
 
 const GrammarError = require( "./grammar-error" );
+const ast = require( "./ast" );
 const compiler = require( "./compiler" );
 const parser = require( "./parser" );
 const util = require( "./util" );
@@ -10,6 +11,7 @@ const peg = {
     VERSION: "0.11.0-dev",
 
     GrammarError: GrammarError,
+    ast: ast,
     parser: parser,
     compiler: compiler,
     util: util,
diff --git a/lib/typings/api.d.ts b/lib/typings/api.d.ts
index 25b4ba4..32ea1ed 100644
--- a/lib/typings/api.d.ts
+++ b/lib/typings/api.d.ts
@@ -5,7 +5,7 @@ export as namespace peg;
 
 declare namespace peg {
 
-    type AST = parser.Grammar;
+    type Grammar = ast.Grammar;
     type GeneratedParser<T = any> = gp.API<T>;
     type SyntaxError = gp.SyntaxErrorConstructor;
     type SourceLocation = gp.SourceLocation;
@@ -28,13 +28,10 @@ declare namespace peg {
 
     }
 
-    /**
-     * A generated PEG.js parser to parse PEG.js grammar source's.
-     */
-    namespace parser {
+    namespace ast {
 
         /**
-         * PEG.js node constructor, used internally by the PEG.js to create nodes.
+         * PEG.js node constructor, used internally by the PEG.js parser to create nodes.
          */
         class Node {
 
@@ -54,20 +51,20 @@ declare namespace peg {
 
             private readonly _alwaysConsumesOnSuccess: any;
             type: "grammar";
-            comments?: CommentMao;
-            initializer?: ast.Initializer;
-            rules: ast.Rule[];
+            comments?: Comment;
+            initializer?: Initializer;
+            rules: Rule[];
 
             constructor(
-                initializer: void | ast.Initializer,
-                rules: ast.Rule[],
-                comments: void | CommentMao,
+                initializer: void | Initializer,
+                rules: Rule[],
+                comments: void | Comment,
                 location: SourceLocation,
             );
 
-            findRule( name: string ): ast.Rule | void;
+            findRule( name: string ): Rule | void;
             indexOfRule( name: string ): number;
-            alwaysConsumesOnSuccess( node: ast.Node ): boolean;
+            alwaysConsumesOnSuccess( node: Object ): boolean;
 
             // Added by Bytecode generator
 
@@ -82,7 +79,7 @@ declare namespace peg {
 
         }
 
-        interface CommentMao {
+        interface Comment {
 
             [ offset: number ]: {
 
@@ -94,189 +91,234 @@ declare namespace peg {
 
         }
 
+        interface INode extends peg.ast.Node { }
+
         /**
-         * Interface's that describe the abstact sytax tree used by PEG.js
+         * This type represent's all PEG.js AST node's.
          */
-        namespace ast {
+        type Object
+            = Grammar
+            | Initializer
+            | Rule
+            | Named
+            | Expression;
 
-            interface INode extends parser.Node { }
+        interface Initializer extends INode {
 
-            /**
-             * Unlike `parser.Node` this interface represent's all PEG.js node's.
-             */
-            type Node
-                = parser.Grammar
-                | Initializer
-                | Rule
-                | Named
-                | Expression;
+            type: "initializer";
+            code: string;
 
-            interface Initializer extends INode {
+        }
 
-                type: "initializer";
-                code: string;
+        interface Rule extends INode {
 
-            }
+            // Default properties
 
-            interface Rule extends INode {
+            type: "rule",
+            name: string;
+            expression: Named | Expression;
 
-                // Default properties
+            // Added by calc-report-failures pass
 
-                type: "rule",
-                name: string;
-                expression: Named | Expression;
+            reportFailures?: boolean;
 
-                // Added by calc-report-failures pass
+            // Added by inference-match-result pass
 
-                reportFailures?: boolean;
+            match?: number;
 
-                // Added by inference-match-result pass
+            // Added by generate-bytecode pass
 
-                match?: number;
+            bytecode?: number[];
 
-                // Added by generate-bytecode pass
+        }
 
-                bytecode?: number[];
+        interface Named extends INode {
 
-            }
+            type: "named";
+            name: string;
+            expression: Expression;
 
-            interface Named extends INode {
+        }
 
-                type: "named";
-                name: string;
-                expression: Expression;
+        type Expression
+            = ChoiceExpression
+            | ActionExpression
+            | SequenceExpression
+            | LabeledExpression
+            | PrefixedExpression
+            | SuffixedExpression
+            | PrimaryExpression;
 
-            }
+        interface ChoiceExpression extends INode {
 
-            type Expression
-                = ChoiceExpression
-                | ActionExpression
+            type: "choice";
+            alternatives: (
+                ActionExpression
                 | SequenceExpression
                 | LabeledExpression
                 | PrefixedExpression
                 | SuffixedExpression
-                | PrimaryExpression;
+                | PrimaryExpression
+            )[];
 
-            interface ChoiceExpression extends INode {
+        }
 
-                type: "choice";
-                alternatives: (
-                    ActionExpression
-                    | SequenceExpression
-                    | LabeledExpression
-                    | PrefixedExpression
-                    | SuffixedExpression
-                    | PrimaryExpression
-                )[];
+        interface ActionExpression extends INode {
 
-            }
+            type: "action";
+            expression: (
+                SequenceExpression
+                | LabeledExpression
+                | PrefixedExpression
+                | SuffixedExpression
+                | PrimaryExpression
+            );
+            code: string;
 
-            interface ActionExpression extends INode {
+        }
 
-                type: "action";
-                expression: (
-                    SequenceExpression
-                    | LabeledExpression
-                    | PrefixedExpression
-                    | SuffixedExpression
-                    | PrimaryExpression
-                );
-                code: string;
+        interface SequenceExpression extends INode {
 
-            }
+            type: "sequence",
+            elements: (
+                LabeledExpression
+                | PrefixedExpression
+                | SuffixedExpression
+                | PrimaryExpression
+            )[];
 
-            interface SequenceExpression extends INode {
+        }
 
-                type: "sequence",
-                elements: (
-                    LabeledExpression
-                    | PrefixedExpression
-                    | SuffixedExpression
-                    | PrimaryExpression
-                )[];
+        interface LabeledExpression extends INode {
 
-            }
+            type: "labeled";
+            label: string;
+            expression: (
+                PrefixedExpression
+                | SuffixedExpression
+                | PrimaryExpression
+            );
 
-            interface LabeledExpression extends INode {
+        }
 
-                type: "labeled";
-                label: string;
-                expression: (
-                    PrefixedExpression
-                    | SuffixedExpression
-                    | PrimaryExpression
-                );
+        interface PrefixedExpression extends INode {
 
-            }
+            type: "text" | "simple_and" | "simple_not";
+            expression: SuffixedExpression | PrimaryExpression;
+
+        }
 
-            interface PrefixedExpression extends INode {
+        interface SuffixedExpression extends INode {
 
-                type: "text" | "simple_and" | "simple_not";
-                expression: SuffixedExpression | PrimaryExpression;
+            type: "optional" | "zero_or_more" | "one_or_more";
+            expression: PrimaryExpression;
 
-            }
+        }
 
-            interface SuffixedExpression extends INode {
+        type PrimaryExpression
+            = LiteralMatcher
+            | CharacterClassMatcher
+            | AnyMatcher
+            | RuleReferenceExpression
+            | SemanticPredicateExpression
+            | GroupExpression;
 
-                type: "optional" | "zero_or_more" | "one_or_more";
-                expression: PrimaryExpression;
+        interface LiteralMatcher extends INode {
 
-            }
+            type: "literal";
+            value: string;
+            ignoreCase: boolean;
 
-            type PrimaryExpression
-                = LiteralMatcher
-                | CharacterClassMatcher
-                | AnyMatcher
-                | RuleReferenceExpression
-                | SemanticPredicateExpression
-                | GroupExpression;
+        }
 
-            interface LiteralMatcher extends INode {
+        interface CharacterClassMatcher extends INode {
 
-                type: "literal";
-                value: string;
-                ignoreCase: boolean;
+            type: "class";
+            parts: ( string[] | string )[];
+            inverted: boolean;
+            ignoreCase: boolean;
 
-            }
+        }
 
-            interface CharacterClassMatcher extends INode {
+        interface AnyMatcher extends INode {
 
-                type: "class";
-                parts: ( string[] | string )[];
-                inverted: boolean;
-                ignoreCase: boolean;
+            type: "any";
 
-            }
+        }
 
-            interface AnyMatcher extends INode {
+        interface RuleReferenceExpression extends INode {
 
-                type: "any";
+            type: "rule_ref";
+            name: string;
 
-            }
+        }
+
+        interface SemanticPredicateExpression extends INode {
+
+            type: "semantic_and" | "semantic_not";
+            code: string;
+
+        }
 
-            interface RuleReferenceExpression extends INode {
+        interface GroupExpression extends INode {
 
-                type: "rule_ref";
-                name: string;
+            type: "group";
+            expression: LabeledExpression | SequenceExpression;
+
+        }
+
+        namespace visitor {
+
+            interface IVisitorMap<U = void> {
+
+                [ key: string ]: any;
+                grammar?<R = U>( node: Grammar, ...args ): R;
+                initializer?<R = U>( node: Initializer, ...args ): R;
+                rule?<R = U>( node: Rule, ...args ): R;
+                named?<R = U>( node: Named, ...args ): R;
+                choice?<R = U>( node: ChoiceExpression, ...args ): R;
+                action?<R = U>( node: ActionExpression, ...args ): R;
+                sequence?<R = U>( node: SequenceExpression, ...args ): R;
+                labeled?<R = U>( node: LabeledExpression, ...args ): R;
+                text?<R = U>( node: PrefixedExpression, ...args ): R;
+                simple_and?<R = U>( node: PrefixedExpression, ...args ): R;
+                simple_not?<R = U>( node: PrefixedExpression, ...args ): R;
+                optional?<R = U>( node: SuffixedExpression, ...args ): R;
+                zero_or_more?<R = U>( node: SuffixedExpression, ...args ): R;
+                one_or_more?<R = U>( node: SuffixedExpression, ...args ): R;
+                literal?<R = U>( node: LiteralMatcher, ...args ): R;
+                class?<R = U>( node: CharacterClassMatcher, ...args ): R;
+                any?<R = U>( node: AnyMatcher, ...args ): R;
+                rule_ref?<R = U>( node: RuleReferenceExpression, ...args ): R;
+                semantic_and?<R = U>( node: SemanticPredicateExpression, ...args ): R;
+                semantic_not?<R = U>( node: SemanticPredicateExpression, ...args ): R;
+                group?<R = U>( node: GroupExpression, ...args ): R;
 
             }
 
-            interface SemanticPredicateExpression extends INode {
+            class ASTVisitor implements IVisitorMap {
 
-                type: "semantic_and" | "semantic_not";
-                code: string;
+                visit<R = any>( node: Object, ...args ): R;
 
             }
 
-            interface GroupExpression extends INode {
+            interface IVisitor<R = any> {
 
-                type: "group";
-                expression: LabeledExpression | SequenceExpression;
+                ( node: Object, ...args ): R;
 
             }
 
+            function build<T = void, R = any>( functions: IVisitorMap<T> ): IVisitor<R>;
+
         }
 
+    }
+
+    /**
+     * A generated PEG.js parser to parse PEG.js grammar source's.
+     */
+    namespace parser {
+
         const SyntaxError: SyntaxError;
         function parse( input: string, options?: gp.IOptions ): Grammar;
 
@@ -330,48 +372,6 @@ declare namespace peg {
 
         }
 
-        interface IVisitor<R = any> {
-
-            ( node: parser.ast.Node, ...args ): R;
-
-        }
-
-        interface IVisitorMap<U = void> {
-
-            [ key: string ]: any;
-            grammar?<R = U>( node: Grammar, ...args ): R;
-            initializer?<R = U>( node: parser.ast.Initializer, ...args ): R;
-            rule?<R = U>( node: parser.ast.Rule, ...args ): R;
-            named?<R = U>( node: parser.ast.Named, ...args ): R;
-            choice?<R = U>( node: parser.ast.ChoiceExpression, ...args ): R;
-            action?<R = U>( node: parser.ast.ActionExpression, ...args ): R;
-            sequence?<R = U>( node: parser.ast.SequenceExpression, ...args ): R;
-            labeled?<R = U>( node: parser.ast.LabeledExpression, ...args ): R;
-            text?<R = U>( node: parser.ast.PrefixedExpression, ...args ): R;
-            simple_and?<R = U>( node: parser.ast.PrefixedExpression, ...args ): R;
-            simple_not?<R = U>( node: parser.ast.PrefixedExpression, ...args ): R;
-            optional?<R = U>( node: parser.ast.SuffixedExpression, ...args ): R;
-            zero_or_more?<R = U>( node: parser.ast.SuffixedExpression, ...args ): R;
-            one_or_more?<R = U>( node: parser.ast.SuffixedExpression, ...args ): R;
-            literal?<R = U>( node: parser.ast.LiteralMatcher, ...args ): R;
-            class?<R = U>( node: parser.ast.CharacterClassMatcher, ...args ): R;
-            any?<R = U>( node: parser.ast.AnyMatcher, ...args ): R;
-            rule_ref?<R = U>( node: parser.ast.RuleReferenceExpression, ...args ): R;
-            semantic_and?<R = U>( node: parser.ast.SemanticPredicateExpression, ...args ): R;
-            semantic_not?<R = U>( node: parser.ast.SemanticPredicateExpression, ...args ): R;
-            group?<R = U>( node: parser.ast.GroupExpression, ...args ): R;
-
-        }
-
-        class visitor implements IVisitorMap {
-
-            visit: IVisitor;
-
-            static build<T = void, R = any>( functions: IVisitorMap<T> ): IVisitor<R>;
-            static ASTVisitor: visitor;
-
-        }
-
         namespace passes {
 
             namespace check {
diff --git a/lib/typings/modules.d.ts b/lib/typings/modules.d.ts
index d46c558..ff66bfc 100644
--- a/lib/typings/modules.d.ts
+++ b/lib/typings/modules.d.ts
@@ -18,22 +18,40 @@ declare module "pegjs/lib/parser" {
 
 }
 
-declare module "pegjs/lib/parser/ast" {
+declare module "pegjs/lib/peg" {
 
-    export const Node: peg.parser.Node;
-    export const Grammar: peg.parser.Grammar;
+    export default peg;
 
 }
 
-declare module "pegjs/lib/parser/index" {
+declare module "pegjs/lib/ast" {
 
-    export default peg.parser;
+    export const Node: peg.ast.Node;
+    export const Grammar: peg.ast.Grammar;
+    export const visitor: {
+
+        ASTVisitor: peg.ast.visitor.ASTVisitor;
+        build<T = void, R = any>( functions: peg.ast.visitor.IVisitorMap<T> ): peg.ast.visitor.IVisitor<R>;
+
+    };
 
 }
 
-declare module "pegjs/lib/peg" {
+declare module "pegjs/lib/ast/Grammar" {
 
-    export default peg;
+    export default peg.ast.Grammar;
+
+}
+
+declare module "pegjs/lib/ast/Node" {
+
+    export default peg.ast.Node;
+
+}
+
+declare module "pegjs/lib/ast/visitor" {
+
+    export default peg.ast.visitor;
 
 }
 
@@ -68,12 +86,6 @@ declare module "pegjs/lib/compiler/opcodes" {
 
 }
 
-declare module "pegjs/lib/compiler/visitor" {
-
-    export default peg.compiler.visitor;
-
-}
-
 declare module "pegjs/lib/compiler/passes/calc-report-failures" {
 
     export default peg.compiler.passes.generate.calcReportFailures;
diff --git a/src/grammar.pegjs b/src/parser.pegjs
similarity index 100%
rename from src/grammar.pegjs
rename to src/parser.pegjs
diff --git a/src/pegjs.config.js b/src/pegjs.config.js
index d0d1620..2f14601 100644
--- a/src/pegjs.config.js
+++ b/src/pegjs.config.js
@@ -7,7 +7,7 @@ module.exports = {
     dependencies: {
 
         ast: "./ast",
-        util: "../util"
+        util: "./util"
 
     },
 
diff --git a/test/spec/api/plugin-api.spec.js b/test/spec/api/plugin-api.spec.js
index 84b819d..fb64885 100644
--- a/test/spec/api/plugin-api.spec.js
+++ b/test/spec/api/plugin-api.spec.js
@@ -103,11 +103,11 @@ describe( "plugin API", function () {
                     config.parser = peg.generate( `
 
                         {
-                            const pp = require( process.cwd() + "/lib/peg" ).parser;
+                            const ast = require( process.cwd() + "/lib/ast" );
                         }
 
                         start = .* {
-                            return new pp.Grammar( void 0, [{
+                            return new ast.Grammar( void 0, [{
                                 type: "rule",
                                 name: "start",
                                 expression: {
diff --git a/test/spec/unit/parser.spec.js b/test/spec/unit/parser.spec.js
index 52820dd..a87e319 100644
--- a/test/spec/unit/parser.spec.js
+++ b/test/spec/unit/parser.spec.js
@@ -3,6 +3,7 @@
 const chai = require( "chai" );
 const parser = require( "pegjs-dev" ).parser;
 const util = require( "pegjs-dev" ).util;
+const visitor = require( "pegjs-dev" ).ast.visitor;
 
 const expect = chai.expect;
 
@@ -167,16 +168,6 @@ describe( "PEG.js grammar parser", function () {
 
         let strip;
 
-        function buildVisitor( functions ) {
-
-            return function ( node ) {
-
-                return functions[ node.type ].apply( null, arguments );
-
-            };
-
-        }
-
         function stripLeaf( node ) {
 
             delete node.location;
@@ -203,7 +194,7 @@ describe( "PEG.js grammar parser", function () {
 
         }
 
-        strip = buildVisitor( {
+        strip = visitor.build( {
             grammar( node ) {
 
                 delete node.location;