Revert "Optimize JSON parsing a bit (#14366)" (#14804)

This reverts commit 9ef6366.

spec/std/json/parser_spec.cr

@@ -2,13 +2,9 @@ require "spec"
 require "json"
 
 private def it_parses(string, expected_value, file = __FILE__, line = __LINE__)
-  it "parses #{string} from String", file, line do
+  it "parses #{string}", file, line do
     JSON.parse(string).raw.should eq(expected_value)
   end
-
-  it "parses #{string} from IO", file, line do
-    JSON.parse(IO::Memory.new(string)).raw.should eq(expected_value)
-  end
 end
 
 private def it_raises_on_parse(string, file = __FILE__, line = __LINE__)
@@ -35,7 +31,6 @@ describe JSON::Parser do
   it_parses "[true]", [true]
   it_parses "[false]", [false]
   it_parses %(["hello"]), ["hello"]
-  it_parses %(["hello", 1]), ["hello", 1]
   it_parses "[0]", [0]
   it_parses " [ 0 ] ", [0]
 

spec/std/json/pull_parser_spec.cr

@@ -92,8 +92,8 @@ class JSON::PullParser
   end
 end
 
-private def assert_pull_parse(string, file = __FILE__, line = __LINE__)
-  it "parses #{string}", file, line do
+private def assert_pull_parse(string)
+  it "parses #{string}" do
     parser = JSON::PullParser.new string
     parser.assert JSON.parse(string).raw
     parser.kind.should eq(JSON::PullParser::Kind::EOF)

src/json/lexer.cr

@@ -220,16 +220,8 @@ abstract class JSON::Lexer
   private def consume_number
     number_start
 
-    # Integer values of up to 18 digits can be computed by doing math:
-    # no need to store a string value and later parse it.
-    # For larger numbers, or floats, we store the entire string and later parse it.
-    @token.int_value = nil
-    integer = 0_i64
-    negative = false
-
     if current_char == '-'
       append_number_char
-      negative = true
       next_char
     end
 
@@ -246,19 +238,13 @@ abstract class JSON::Lexer
         unexpected_char
       else
         @token.kind = :int
-        @token.int_value = 0
         number_end
       end
     when '1'..'9'
       append_number_char
-      digits = 1
-      integer = (current_char - '0').to_i64
       char = next_char
       while '0' <= char <= '9'
         append_number_char
-        digits += 1
-        integer &*= 10
-        integer &+= char - '0'
         char = next_char
       end
 
@@ -269,13 +255,7 @@ abstract class JSON::Lexer
         consume_exponent
       else
         @token.kind = :int
-        # Int64::MAX is 9223372036854775807 which has 19 digits.
-        # With 18 digits we know the number we computed is the one we read.
-        if digits > 18
-          number_end
-        else
-          @token.int_value = negative ? -integer : integer
-        end
+        number_end
       end
     else
       unexpected_char

src/json/lexer/io_based.cr

@@ -2,64 +2,17 @@
 class JSON::Lexer::IOBased < JSON::Lexer
   def initialize(@io : IO)
     super()
-    @current_char = @io.read_byte.try(&.chr) || '\0'
+    @current_char = @io.read_char || '\0'
   end
 
   private getter current_char
 
   private def next_char_no_column_increment
-    @current_char = @io.read_byte.try(&.chr) || '\0'
+    @current_char = @io.read_char || '\0'
   end
 
   private def consume_string
-    peek = @io.peek
-    if !peek || peek.empty?
-      return consume_string_with_buffer
-    end
-
-    pos = 0
-
-    while true
-      if pos >= peek.size
-        # We don't have enough data in the peek buffer to create a string:
-        # default to the slow method
-        return consume_string_with_buffer
-      end
-
-      char = peek[pos]
-      case char
-      when '\\'
-        # If we find an escape character, go to the slow method
-        @column_number += pos
-        return consume_string_at_escape_char(peek, pos)
-      when '"'
-        break
-      else
-        if 0 <= current_char.ord < 32
-          unexpected_char
-        else
-          pos += 1
-        end
-      end
-    end
-
-    @column_number += pos
-    @token.string_value =
-      if @expects_object_key
-        @string_pool.get(peek.to_unsafe, pos)
-      else
-        String.new(peek.to_unsafe, pos)
-      end
-
-    @io.skip(pos + 1)
-    next_char
-  end
-
-  private def consume_string_at_escape_char(peek, pos)
-    consume_string_with_buffer do
-      @buffer.write peek[0, pos]
-      @io.skip(pos)
-    end
+    consume_string_with_buffer
   end
 
   private def number_start

src/json/lexer/string_based.cr

@@ -1,9 +1,8 @@
 # :nodoc:
 class JSON::Lexer::StringBased < JSON::Lexer
-  def initialize(string : String)
+  def initialize(string)
     super()
-    @string = string
-    @pos = 0
+    @reader = Char::Reader.new(string)
     @number_start = 0
   end
 
@@ -34,7 +33,7 @@ class JSON::Lexer::StringBased < JSON::Lexer
     if @expects_object_key
       start_pos += 1
       end_pos = current_pos - 1
-      @token.string_value = @string_pool.get(@string.to_unsafe + start_pos, end_pos - start_pos)
+      @token.string_value = @string_pool.get(@reader.string.to_unsafe + start_pos, end_pos - start_pos)
     else
       @token.string_value = string_range(start_pos + 1, current_pos - 1)
     end
@@ -48,30 +47,27 @@ class JSON::Lexer::StringBased < JSON::Lexer
   end
 
   private def current_pos
-    @pos
+    @reader.pos
   end
 
   def string_range(start_pos, end_pos) : String
-    @string.byte_slice(start_pos, end_pos - start_pos)
+    @reader.string.byte_slice(start_pos, end_pos - start_pos)
   end
 
   def slice_range(start_pos, end_pos) : Bytes
-    @string.to_slice[start_pos, end_pos - start_pos]
+    @reader.string.to_slice[start_pos, end_pos - start_pos]
   end
 
   private def next_char_no_column_increment
-    @pos += 1
-
-    char = current_char
-    if char == '\0' && @pos != @string.bytesize
+    char = @reader.next_char
+    if char == '\0' && @reader.pos != @reader.string.bytesize
       unexpected_char
     end
-
     char
   end
 
   private def current_char
-    @string.to_unsafe[@pos].chr
+    @reader.current_char
   end
 
   private def number_start

src/json/token.cr

@@ -19,7 +19,7 @@ class JSON::Token
   property string_value : String
 
   def int_value : Int64
-    @int_value || raw_value.to_i64
+    raw_value.to_i64
   rescue exc : ArgumentError
     raise ParseException.new(exc.message, line_number, column_number)
   end
@@ -32,25 +32,14 @@ class JSON::Token
 
   property line_number : Int32
   property column_number : Int32
-  setter raw_value : String
-  setter int_value : Int64?
+  property raw_value : String
 
   def initialize
     @kind = :EOF
     @line_number = 0
     @column_number = 0
     @string_value = ""
     @raw_value = ""
-    @int_value = nil
-  end
-
-  def raw_value
-    case @kind
-    when .int?
-      @int_value.try(&.to_s) || @raw_value
-    else
-      @raw_value
-    end
   end
 
   def to_s(io : IO) : Nil
@@ -62,11 +51,7 @@ class JSON::Token
     when .true?
       io << "true"
     when .int?
-      if int_value = @int_value
-        int_value.to_s(io)
-      else
-        raw_value.to_s(io)
-      end
+      raw_value.to_s(io)
     when .float?
       raw_value.to_s(io)
     when .string?