public static IEnumerable<StatementSyntax> LopsidedTerminalBranchesToGuardedBranches(IfStatementSyntax syntax)
{
Contract.Requires(syntax != null);
Contract.Requires(syntax.Parent is BlockSyntax);
if (syntax.Statement.IsGuaranteedToJumpOut()) return new[] { syntax };
if (syntax.Else != null && syntax.Else.Statement.IsGuaranteedToJumpOut()) return new[] { syntax };
var allowedJump = syntax.TryGetEquivalentJumpAfterStatement();
if (allowedJump == null) return new[] { syntax };
var trueBloat = syntax.Statement.Bloat();
var falseBloat = syntax.Else == null ? 0 : syntax.Else.Statement.Bloat();
if (trueBloat < falseBloat * 2 - 10) {
// inline the false branch, guard with the true branch
return syntax.Else.Statement.Statements().Prepend(
syntax.WithStatement(syntax.Statement.BracedTo(syntax.Statement.Statements().Concat(new[] {allowedJump})))
.WithElse(null));
}
if (falseBloat < trueBloat * 2 - 10) {
// inline the true branch, guard with the false branch
return syntax.Statement.Statements().Prepend(
syntax.WithCondition(syntax.Condition.Inverted())
.WithStatement(syntax.Else == null ? allowedJump : syntax.Else.Statement.BracedTo(syntax.Else.Statement.Statements().Concat(new[] {allowedJump})))
.WithElse(null));
}
return new[] { syntax };
}