Force the maintaining of the modifier forms of conditionals and loops if the statement includes an assignment. Also, for the maintaining of the block form of conditionals and loops if the predicate includes an assignment.

Author: kddnewton

CHANGELOG.md

@@ -10,6 +10,7 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/) a
 
 - [#7](https://github.com/kddnewton/syntax_tree/issues/7) Better formatting for hashes and arrays that are values in hashes.
 - [#9](https://github.com/kddnewton/syntax_tree/issues/9) Special handling for RSpec matchers when nesting `CommandCall` nodes.
+- [#10](https://github.com/kddnewton/syntax_tree/issues/10) Force the maintaining of the modifier forms of conditionals and loops if the statement includes an assignment. Also, for the maintaining of the block form of conditionals and loops if the predicate includes an assignment.
 
 ## [1.1.0] - 2021-12-08
 

lib/syntax_tree.rb

@@ -1654,7 +1654,7 @@ def initialize(
     end
 
     def child_nodes
-      [constant, *required, rest, *posts]
+      [constant, *requireds, rest, *posts]
     end
 
     def format(q)
@@ -6784,6 +6784,23 @@ def on_ident(value)
     )
   end
 
+  # If the predicate of a conditional or loop contains an assignment (in which
+  # case we can't know for certain that that assignment doesn't impact the
+  # statements inside the conditional) then we can't use the modifier form
+  # and we must use the block form.
+  module ContainsAssignment
+    def self.call(parent)
+      queue = [parent]
+
+      while node = queue.shift
+        return true if [Assign, MAssign, OpAssign].include?(node.class)
+        queue += node.child_nodes
+      end
+
+      false
+    end
+  end
+
   # Formats an If or Unless node.
   class ConditionalFormatter
     # [String] the keyword associated with this conditional
@@ -6802,7 +6819,7 @@ def format(q)
       # case we can't know for certain that that assignment doesn't impact the
       # statements inside the conditional) then we can't use the modifier form
       # and we must use the block form.
-      if [Assign, MAssign, OpAssign].include?(node.predicate.class)
+      if ContainsAssignment.call(node.predicate)
         format_break(q, force: true)
         return
       end
@@ -7078,23 +7095,31 @@ def initialize(keyword, node)
     end
 
     def format(q)
-      q.group do
-        q.if_break do
-          q.text("#{keyword} ")
-          q.nest(keyword.length + 1) { q.format(node.predicate) }
-          q.indent do
-            q.breakable
-            q.format(node.statement)
-          end
-          q.breakable
-          q.text("end")
-        end.if_flat do
-          Parentheses.flat(q) do
-            q.format(node.statement)
-            q.text(" #{keyword} ")
-            q.format(node.predicate)
-          end
-        end
+      if ContainsAssignment.call(node.statement)
+        q.group { format_flat(q) }
+      else
+        q.group { q.if_break { format_break(q) }.if_flat { format_flat(q) } }
+      end
+    end
+
+    private
+
+    def format_break(q)
+      q.text("#{keyword} ")
+      q.nest(keyword.length + 1) { q.format(node.predicate) }
+      q.indent do
+        q.breakable
+        q.format(node.statement)
+      end
+      q.breakable
+      q.text("end")
+    end
+
+    def format_flat(q)
+      Parentheses.flat(q) do
+        q.format(node.statement)
+        q.text(" #{keyword} ")
+        q.format(node.predicate)
       end
     end
   end
@@ -12436,11 +12461,7 @@ def initialize(keyword, node, statements)
     end
 
     def format(q)
-      # If the predicate of the loop contains an assignment (in which case we
-      # can't know for certain that that assignment doesn't impact the
-      # statements inside the loop) then we can't use the modifier form and we
-      # must use the block form.
-      if [Assign, MAssign, OpAssign].include?(node.predicate.class)
+      if ContainsAssignment.call(node.predicate)
         format_break(q)
         q.break_parent
         return
@@ -12601,8 +12622,13 @@ def format(q)
       #       foo
       #     end until bar
       #
-      # The above is effectively a `do...until` loop.
-      if statement.is_a?(Begin)
+      # Also, if the statement of the modifier includes an assignment, then we
+      # can't know for certain that it won't impact the predicate, so we need to
+      # force it to stay as it is. This looks like:
+      #
+      #     foo = bar until foo
+      #
+      if statement.is_a?(Begin) || ContainsAssignment.call(statement)
         q.format(statement)
         q.text(" until ")
         q.format(predicate)
@@ -13189,8 +13215,13 @@ def format(q)
       #       foo
       #     end while bar
       #
-      # The above is effectively a `do...while` loop.
-      if statement.is_a?(Begin)
+      # Also, if the statement of the modifier includes an assignment, then we
+      # can't know for certain that it won't impact the predicate, so we need to
+      # force it to stay as it is. This looks like:
+      #
+      #     foo = bar while foo
+      #
+      if statement.is_a?(Begin) || ContainsAssignment.call(statement)
         q.format(statement)
         q.text(" while ")
         q.format(predicate)

test/fixtures/if.rb

@@ -24,3 +24,7 @@
 if foo += 1
   foo
 end
+%
+if (foo += 1)
+  foo
+end

test/fixtures/if_mod.rb

@@ -8,3 +8,8 @@
 end
 %
 bar if foo # comment
+%
+foo = barrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr if foo
+-
+foo =
+  barrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr if foo

test/fixtures/unless.rb

@@ -24,3 +24,7 @@
 unless foo += 1
   foo
 end
+%
+unless (foo += 1)
+  foo
+end

test/fixtures/unless_mod.rb

@@ -8,3 +8,8 @@
 end
 %
 bar unless foo # comment
+%
+foo = barrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr unless foo
+-
+foo =
+  barrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr unless foo

test/fixtures/until.rb

@@ -19,3 +19,7 @@
 until foo += 1
   foo
 end
+%
+until (foo += 1)
+  foo
+end

test/fixtures/until_mod.rb

@@ -8,3 +8,8 @@
 end
 %
 bar until foo # comment
+%
+foo = barrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr until foo
+-
+foo =
+  barrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr until foo

test/fixtures/while.rb

@@ -19,3 +19,7 @@
 while foo += 1
   foo
 end
+%
+while (foo += 1)
+  foo
+end

test/fixtures/while_mod.rb

@@ -8,3 +8,8 @@
 end
 %
 bar while foo # comment
+%
+foo = barrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr while foo
+-
+foo =
+  barrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr while foo