Improve Builder performance

README.md

@@ -69,18 +69,17 @@ There are benchmarks comparing `CON` and the stdlib's `JSON` implementation
 Some results:
 
 ```
- CON.parse minified 636.54k (  1.57µs) (± 3.02%)  1936 B/op        fastest
-   CON.parse pretty 572.87k (  1.75µs) (± 1.32%)  1936 B/op   1.11× slower
-JSON.parse minified 562.57k (  1.78µs) (± 1.80%)  2128 B/op   1.13× slower
-  JSON.parse pretty 477.41k (  2.09µs) (± 3.85%)  2128 B/op   1.33× slower
+ CON.parse minified 403.83k (  2.48µs) (± 4.67%)  1937 B/op        fastest
+   CON.parse pretty 383.93k (   2.6µs) (± 3.35%)  1936 B/op   1.05× slower
+JSON.parse minified 322.33k (   3.1µs) (± 3.63%)  2129 B/op   1.25× slower
+  JSON.parse pretty  277.7k (   3.6µs) (± 3.82%)  2129 B/op   1.45× slower
 ```
 
 ```
- CON::Builder minified   1.24M (807.52ns) (± 2.04%)   320 B/op        fastest
-   CON::Builder pretty 674.25k (  1.48µs) (±19.03%)  1057 B/op   1.84× slower
-JSON::Builder minified 853.06k (  1.17µs) (± 7.70%)   576 B/op   1.45× slower
-  JSON::Builder pretty 703.44k (  1.42µs) (± 6.03%)   848 B/op   1.76× slower
-
+        #to_con 896.16k (  1.12µs) (± 5.23%)  321 B/op        fastest
+ #to_pretty_con  865.9k (  1.15µs) (± 1.93%)  321 B/op   1.03× slower
+       #to_json 644.32k (  1.55µs) (± 2.49%)  578 B/op   1.39× slower
+#to_pretty_json 515.68k (  1.94µs) (± 2.28%)  849 B/op   1.74× slower
 ```
 
 ## License

benchmark/builder.cr

@@ -3,19 +3,19 @@ require "json"
 require "../src/any"
 
 Benchmark.ips do |x|
-  x.report("CON::Builder minified") do
+  x.report("#to_con") do
     DATA.to_con
   end
 
-  x.report("CON::Builder pretty") do
+  x.report("#to_pretty_con") do
     DATA.to_pretty_con
   end
 
-  x.report("JSON::Builder minified") do
+  x.report("#to_json") do
     DATA.to_json
   end
 
-  x.report("JSON::Builder pretty") do
+  x.report("#to_pretty_json") do
     DATA.to_pretty_json
   end
 end

spec/builder_spec.cr

@@ -104,11 +104,16 @@ describe CON::Builder do
     end
   end
 
-  it "writes hash with indent" do
-    assert_built(%<  foo 1\n  bar 2\n>, "  ") do |con|
+  it "writes nested hash with indent" do
+    assert_built(%<foo 1\nbar {\n  foobar 2\n  sub {\n    key nil\n  }\n}\n>, "  ") do |con|
       hash do
         field "foo", 1
-        field "bar", 2
+        hash "bar" do
+          field "foobar", 2
+          hash "sub" do
+            field "key", nil
+          end
+        end
       end
     end
   end
@@ -127,18 +132,18 @@ describe CON::Builder do
     end
   end
 
-  it "writes nested array" do
-    assert_built(%<[[\n]\n]>, "  ") do |con|
+  it "writes nested array with indent" do
+    assert_built(%<[[\n  ]\n]>, "  ") do |con|
       array do
         array do
         end
       end
     end
   end
 
-  it "writes hash with array and indent" do
-    assert_built(%<foo {\n[\n  1\n]\n}>, "  ") do |con|
-      hash "foo" do
+  it "writes document with array and indent" do
+    assert_built(%<[\n  1\n]>, "  ") do |con|
+      hash do
         array do
           value 1
         end
@@ -199,15 +204,15 @@ describe CON::Builder do
   it "errors on max nesting (object)" do
     builder = CON::Builder.new IO::Memory.new
     builder.max_nesting = 3
-    builder.hash do
-      builder.hash do
-        builder.hash do
+    builder.hash "a" do
+      builder.hash "a" do
+        builder.hash "a" do
         end
       end
     end
 
     expect_raises(CON::Builder::Error, "Nesting of 4 is too deep") do
-      builder.hash do
+      builder.hash "a" do
       end
     end
   end

spec/to_con_spec.cr

@@ -137,11 +137,11 @@ describe "to_pretty_con" do
   end
 
   it "does for Hash" do
-    {"foo" => 1, "bar" => 2}.to_pretty_con.should eq "  foo 1\n  bar 2\n"
+    {"foo" => 1, "bar" => 2}.to_pretty_con.should eq "foo 1\nbar 2\n"
   end
 
   it "does for nested Hash" do
-    {"foo" => {"bar" => 1}}.to_pretty_con.should eq "  foo {\n    bar 1\n\n  }\n"
+    {"foo" => {"bar" => 1}}.to_pretty_con.should eq "foo {\n  bar 1\n}\n\n"
   end
 
   it "does for empty Hash" do
@@ -153,7 +153,7 @@ describe "to_pretty_con" do
   end
 
   it "does for nested Hash with indent" do
-    {"foo" => {"bar" => 1}}.to_pretty_con(indent: " ").should eq " foo {\n  bar 1\n\n }\n"
+    {"foo" => {"bar" => 1}}.to_pretty_con(indent: " ").should eq "foo {\n bar 1\n}\n\n"
   end
 
   describe "Time" do

src/builder.cr

@@ -7,52 +7,43 @@ module CON
 
     getter io : IO
     property max_nesting : Int32 = 99
-    @nest = 0
-    @total_indent : String
-    @previous_total_indent : String?
+    @nest : Int32 = 0
     @indent : String?
     @root_document = false
     @begin_hash = false
     @begin_array = false
 
     def initialize(@io : IO, @indent : String? = nil)
-      @total_indent = @indent || ""
-      @previous_total_indent = nil
       # Not needed at the start/end of a document
       @root_document = true
       @begin_hash = true
     end
 
-    protected def initialize(@io : IO, indent : String?, @total_indent : String, @nest : Int32)
-      # Increment the indentation, if any
-      if @indent = indent
-        @previous_total_indent = @total_indent
-        @total_indent += indent
-      end
+    protected def initialize(@io : IO, @indent : String?, @nest)
     end
 
     def field(key, value)
       if @begin_array
         raise CON::Builder::Error.new("Can't use field inside an array")
       elsif @indent
-        @io << @total_indent
+        add_indent
       elsif @begin_hash
         @begin_hash = false
       else
         @io << ' '
       end
       key.to_s.to_con_key self
       @io << ' '
-      value.to_con Builder.new(@io, @indent, @total_indent, @nest)
+      value.to_con Builder.new(@io, @indent, @nest)
       @io << '\n' if @indent
     end
 
     def value(value)
       if @begin_hash && !@root_document
         raise CON::Builder::Error.new("Can't use value inside a hash")
-      elsif indent = @indent
-        @total_indent = indent if @total_indent.empty?
-        io << '\n' << @total_indent
+      elsif @indent
+        io << '\n'
+        add_indent
       elsif @root_document
         @begin_hash = true
         @root_document = false
@@ -61,13 +52,13 @@ module CON
       else
         @io << ' '
       end
-      value.to_con Builder.new(@io, @indent, @total_indent, @nest)
+      value.to_con Builder.new(@io, @indent, @nest)
     end
 
     private def key(value)
-      if @previous_total_indent
-        @io << '\n' << @previous_total_indent
-      elsif !@indent && !@begin_hash && !@begin_array
+      if @indent
+        add_indent
+      elsif !@begin_hash && !@begin_array
         @io << ' '
       end
       value.to_con_key self
@@ -80,16 +71,22 @@ module CON
     end
 
     def array(&block)
-      increment_nest
+      array_nest = @nest
       io << '['
+      increment_nest
       @begin_array = true
       @begin_hash = false
       previous_root_document = @root_document
       @root_document = false
       yield
       @root_document = previous_root_document
-      io << '\n' if @indent
-      io << @previous_total_indent << ']'
+      if @indent
+        @io << '\n'
+        array_nest.times do
+          @io << @indent
+        end
+      end
+      @io << ']'
     end
 
     def hash(key : String, &block)
@@ -102,16 +99,22 @@ module CON
     end
 
     def hash(&block)
-      increment_nest
       @begin_hash = true
       if @root_document
         yield
       else
+        hash_nest = @nest
+        increment_nest
         @io << '{'
         @io << '\n' if @indent
         yield
+        if @indent
+          hash_nest.times do
+            @io << @indent
+          end
+        end
+        @io << '}'
         @io << '\n' if @indent
-        @io << @previous_total_indent << '}'
       end
       @begin_hash = false
     end
@@ -121,6 +124,18 @@ module CON
         raise CON::Builder::Error.new("Nesting of #{@nest} is too deep")
       end
     end
+
+    private def add_indent
+      @nest.times do
+        @io << @indent
+      end
+    end
+
+    private def add_previous_indent
+      (@nest - 1).times do
+        @io << @indent
+      end
+    end
   end
 
   # Returns the resulting `String` of writing CON to the yielded `CON::Builder`.

src/lexer.cr

@@ -64,19 +64,19 @@ module CON::Lexer::Main
     skip_whitespaces_and_comments
     @buffer.clear
     value = case @current_char
-    when '"'      then next_char; consume_string
-    when '['      then next_char; Token::BeginArray
-    when ']'      then next_char; Token::EndArray
-    when '{'      then next_char; Token::BeginHash
-    when '}'      then next_char; Token::EndHash
-    when 't'      then consume_true
-    when 'f'      then consume_false
-    when 'n'      then consume_nil
-    when '-'      then consume_int(negative: true)
-    when '0'..'9' then consume_int
-    when '\0'     then Token::EOF
-    else               raise "Unknown char: '#{@current_char}'"
-    end
+            when '"'      then next_char; consume_string
+            when '['      then next_char; Token::BeginArray
+            when ']'      then next_char; Token::EndArray
+            when '{'      then next_char; Token::BeginHash
+            when '}'      then next_char; Token::EndHash
+            when 't'      then consume_true
+            when 'f'      then consume_false
+            when 'n'      then consume_nil
+            when '-'      then consume_int(negative: true)
+            when '0'..'9' then consume_int
+            when '\0'     then Token::EOF
+            else               raise "Unknown char: '#{@current_char}'"
+            end
     @column_number = 1
     value
   end