Avoid exposing internal classes from the cassowary library

packages/cassowary/lib/cassowary.dart

-// Copyright (c) 2015, <your name>. All rights reserved. Use of this source code
-// is governed by a BSD-style license that can be found in the LICENSE file.
+// Copyright (c) 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
 
-/// The cassowary library.
 library cassowary;
 
 part 'constraint.dart';

packages/cassowary/lib/constant_member.dart

@@ -4,7 +4,7 @@
 
 part of cassowary;
 
-class ConstantMember extends EquationMember {
+class ConstantMember extends _EquationMember {
   double value = 0.0;
 
   bool get isConstant => true;

packages/cassowary/lib/equation_member.dart

@@ -4,26 +4,26 @@
 
 part of cassowary;
 
-abstract class EquationMember {
+abstract class _EquationMember {
   Expression asExpression();
 
   bool get isConstant;
 
   double get value;
 
-  Constraint operator >=(EquationMember m) => asExpression() >= m;
+  Constraint operator >=(_EquationMember m) => asExpression() >= m;
 
-  Constraint operator <=(EquationMember m) => asExpression() <= m;
+  Constraint operator <=(_EquationMember m) => asExpression() <= m;
 
-  /* Constraint */ operator ==(EquationMember m) => asExpression() == m;
+  /* Constraint */ operator ==(_EquationMember m) => asExpression() == m;
 
-  Expression operator +(EquationMember m) => asExpression() + m;
+  Expression operator +(_EquationMember m) => asExpression() + m;
 
-  Expression operator -(EquationMember m) => asExpression() - m;
+  Expression operator -(_EquationMember m) => asExpression() - m;
 
-  Expression operator *(EquationMember m) => asExpression() * m;
+  Expression operator *(_EquationMember m) => asExpression() * m;
 
-  Expression operator /(EquationMember m) => asExpression() / m;
+  Expression operator /(_EquationMember m) => asExpression() / m;
 
   int get hashCode =>
       throw "An equation member is not comparable and cannot be added to collections";

packages/cassowary/lib/expression.dart

@@ -4,7 +4,7 @@
 
 part of cassowary;
 
-class Expression extends EquationMember {
+class Expression extends _EquationMember {
   final List<Term> terms;
 
   final double constant;
@@ -21,7 +21,7 @@ class Expression extends EquationMember {
   Expression asExpression() => this;
 
   Constraint _createConstraint(
-      EquationMember /* rhs */ value, Relation relation) {
+      _EquationMember /* rhs */ value, Relation relation) {
     if (value is ConstantMember) {
       return new Constraint(
           new Expression(new List.from(terms), constant - value.value),
@@ -51,16 +51,16 @@ class Expression extends EquationMember {
     return null;
   }
 
-  Constraint operator >=(EquationMember value) =>
+  Constraint operator >=(_EquationMember value) =>
       _createConstraint(value, Relation.greaterThanOrEqualTo);
 
-  Constraint operator <=(EquationMember value) =>
+  Constraint operator <=(_EquationMember value) =>
       _createConstraint(value, Relation.lessThanOrEqualTo);
 
-  operator ==(EquationMember value) =>
+  operator ==(_EquationMember value) =>
       _createConstraint(value, Relation.equalTo);
 
-  Expression operator +(EquationMember m) {
+  Expression operator +(_EquationMember m) {
     if (m is ConstantMember) {
       return new Expression(new List.from(terms), constant + m.value);
     }
@@ -83,7 +83,7 @@ class Expression extends EquationMember {
     return null;
   }
 
-  Expression operator -(EquationMember m) {
+  Expression operator -(_EquationMember m) {
     if (m is ConstantMember) {
       return new Expression(new List.from(terms), constant - m.value);
     }
@@ -109,13 +109,13 @@ class Expression extends EquationMember {
     return null;
   }
 
-  EquationMember _applyMultiplicand(double m) {
+  _EquationMember _applyMultiplicand(double m) {
     var newTerms = terms.fold(new List<Term>(), (list, term) => list
       ..add(new Term(term.variable, term.coefficient * m)));
     return new Expression(newTerms, constant * m);
   }
 
-  _Pair<Expression, double> _findMulitplierAndMultiplicand(EquationMember m) {
+  _Pair<Expression, double> _findMulitplierAndMultiplicand(_EquationMember m) {
     // At least on of the the two members must be constant for the resulting
     // expression to be linear
 
@@ -135,7 +135,7 @@ class Expression extends EquationMember {
     return null;
   }
 
-  EquationMember operator *(EquationMember m) {
+  _EquationMember operator *(_EquationMember m) {
     _Pair<Expression, double> args = _findMulitplierAndMultiplicand(m);
 
     if (args == null) {
@@ -147,7 +147,7 @@ class Expression extends EquationMember {
     return args.first._applyMultiplicand(args.second);
   }
 
-  EquationMember operator /(EquationMember m) {
+  _EquationMember operator /(_EquationMember m) {
     if (!m.isConstant) {
       throw new ParserException(
           "The divisor was not a constant expression", [this, m]);

packages/cassowary/lib/param.dart

@@ -4,7 +4,7 @@
 
 part of cassowary;
 
-class Param extends EquationMember {
+class Param extends _EquationMember {
   final Variable variable;
 
   Param.withVariable(this.variable);

packages/cassowary/lib/parser_exception.dart

@@ -6,7 +6,7 @@ part of cassowary;
 
 class ParserException implements Exception {
   final String message;
-  List<EquationMember> members;
+  List<_EquationMember> members;
   ParserException(this.message, this.members);
 
   String toString() {

packages/cassowary/lib/row.dart

@@ -4,18 +4,18 @@
 
 part of cassowary;
 
-class Row {
-  final Map<Symbol, double> cells;
+class _Row {
+  final Map<_Symbol, double> cells;
   double constant = 0.0;
 
-  Row(this.constant) : this.cells = new Map<Symbol, double>();
-  Row.fromRow(Row row)
-      : this.cells = new Map<Symbol, double>.from(row.cells),
+  _Row(this.constant) : this.cells = new Map<_Symbol, double>();
+  _Row.fromRow(_Row row)
+      : this.cells = new Map<_Symbol, double>.from(row.cells),
         this.constant = row.constant;
 
   double add(double value) => constant += value;
 
-  void insertSymbol(Symbol symbol, [double coefficient = 1.0]) {
+  void insertSymbol(_Symbol symbol, [double coefficient = 1.0]) {
     double val = _elvis(cells[symbol], 0.0) + coefficient;
 
     if (_nearZero(val)) {
@@ -25,18 +25,18 @@ class Row {
     }
   }
 
-  void insertRow(Row other, [double coefficient = 1.0]) {
+  void insertRow(_Row other, [double coefficient = 1.0]) {
     constant += other.constant * coefficient;
     other.cells.forEach((s, v) => insertSymbol(s, v * coefficient));
   }
 
-  void removeSymbol(Symbol symbol) {
+  void removeSymbol(_Symbol symbol) {
     cells.remove(symbol);
   }
 
   void reverseSign() => cells.forEach((s, v) => cells[s] = -v);
 
-  void solveForSymbol(Symbol symbol) {
+  void solveForSymbol(_Symbol symbol) {
     assert(cells.containsKey(symbol));
     double coefficient = -1.0 / cells[symbol];
     cells.remove(symbol);
@@ -44,14 +44,14 @@ class Row {
     cells.forEach((s, v) => cells[s] = v * coefficient);
   }
 
-  void solveForSymbols(Symbol lhs, Symbol rhs) {
+  void solveForSymbols(_Symbol lhs, _Symbol rhs) {
     insertSymbol(lhs, -1.0);
     solveForSymbol(rhs);
   }
 
-  double coefficientForSymbol(Symbol symbol) => _elvis(cells[symbol], 0.0);
+  double coefficientForSymbol(_Symbol symbol) => _elvis(cells[symbol], 0.0);
 
-  void substitute(Symbol symbol, Row row) {
+  void substitute(_Symbol symbol, _Row row) {
     double coefficient = cells[symbol];
 
     if (coefficient == null) {

packages/cassowary/lib/symbol.dart

@@ -6,9 +6,9 @@ part of cassowary;
 
 enum SymbolType { invalid, external, slack, error, dummy, }
 
-class Symbol {
+class _Symbol {
   final SymbolType type;
   int tick;
 
-  Symbol(this.type, this.tick);
+  _Symbol(this.type, this.tick);
 }

packages/cassowary/lib/term.dart

@@ -4,7 +4,7 @@
 
 part of cassowary;
 
-class Term extends EquationMember {
+class Term extends _EquationMember {
   final Variable variable;
   final double coefficient;