Use more chars instead of strings (#6237)

samples/2048.cr

@@ -116,7 +116,7 @@ class Drawer
   end
 
   def space_line
-    line "│", " ", "│", "│"
+    line '│', " ", '│', '│'
   end
 
   def content_line
@@ -126,15 +126,15 @@ class Drawer
   end
 
   def top_border
-    line "┌", "─", "┬", "┐"
+    line '┌', "─", '┬', '┐'
   end
 
   def mid_border
-    line "├", "─", "┼", "┤"
+    line '├', "─", '┼', '┤'
   end
 
   def bottom_border
-    line "└", "─", "┴", "┘"
+    line '└', "─", '┴', '┘'
   end
 
   def line(left, fill, inner, right)

samples/havlak.cr

@@ -477,7 +477,7 @@ puts "Another 50 iterations..."
 
 sum = 0
 50.times do |i|
-  print "."
+  print '.'
   sum += HavlakLoopFinder.new(TOP_CFG, LSG.new).find_loops
 end
 

samples/llvm/brainfuck.cr

@@ -5,11 +5,6 @@ require "llvm"
 NUM_CELLS          = 30000
 CELL_SIZE_IN_BYTES =     1
 
-def error(message)
-  puts message
-  exit 1
-end
-
 abstract class Instruction
   abstract def compile(program, bb)
 end
@@ -166,12 +161,12 @@ class Program
       when '['
         matching_close_index = find_matching_close(source, i)
         unless matching_close_index
-          error "Unmatched '[' at position #{i}"
+          abort "Unmatched '[' at position #{i}"
         end
         program << Loop.new(parse(source, i + 1, matching_close_index))
         i = matching_close_index
       when ']'
-        error "Unmatched ']' at position #{i}"
+        abort "Unmatched ']' at position #{i}"
       end
       i += 1
     end
@@ -253,11 +248,11 @@ end
 
 filename = ARGV.first?
 unless filename
-  error "Missing filename"
+  abort "Missing filename"
 end
 
 unless File.file?(filename)
-  error "'#{filename} is not a file"
+  abort "#{filename} is not a file"
 end
 
 source = File.read(filename)

samples/meteor.cr

@@ -130,8 +130,8 @@ def print_sol(str)
   i = 0
   str.each_byte do |c|
     puts if i % 5 == 0
-    print " " if (i + 5) % 10 == 0
-    print " "
+    print ' ' if (i + 5) % 10 == 0
+    print ' '
     print c.chr
     i += 1
   end

spec/compiler/crystal/tools/context_spec.cr

@@ -20,7 +20,7 @@ private def run_context_tool(code)
     end
   end
 
-  code = code.gsub('‸', "")
+  code = code.delete('‸')
 
   if cursor_location
     visitor, result = processed_context_visitor(code, cursor_location)

spec/compiler/crystal/tools/expand_spec.cr

@@ -22,7 +22,7 @@ private def run_expand_tool(code)
     end
   end
 
-  code = code.gsub('‸', "")
+  code = code.delete('‸')
 
   if cursor_location
     visitor, result = processed_expand_visitor(code, cursor_location)
@@ -55,11 +55,11 @@ private def assert_expand(code, expected_result)
   end
 end
 
-private def assert_expand_simple(code, expanded, original = code.gsub('‸', ""))
+private def assert_expand_simple(code, expanded, original = code.delete('‸'))
   assert_expand_simple(code, expanded, original) { }
 end
 
-private def assert_expand_simple(code, expanded, original = code.gsub('‸', ""))
+private def assert_expand_simple(code, expanded, original = code.delete('‸'))
   assert_expand(code, [[original, expanded]]) { |result| yield result.expansions.not_nil![0] }
 end
 

spec/compiler/crystal/tools/implementations_spec.cr

@@ -25,7 +25,7 @@ private def assert_implementations(code)
     end
   end
 
-  code = code.gsub('‸', "").gsub('༓', "")
+  code = code.delete { |char| {'‸', '༓'}.includes? char }
 
   if cursor_location
     visitor, result = processed_implementation_visitor(code, cursor_location)

spec/compiler/lexer/lexer_spec.cr

@@ -125,7 +125,7 @@ end
 private def it_lexes_symbols(symbols)
   symbols.each do |symbol|
     value = symbol[1, symbol.size - 1]
-    value = value[1, value.size - 2] if value.starts_with?("\"")
+    value = value[1, value.size - 2] if value.starts_with?('"')
     it_lexes symbol, :SYMBOL, value
   end
 end

spec/compiler/parser/parser_spec.cr

@@ -74,7 +74,7 @@ module Crystal
      ":>=", ":!", ":!=", ":=~", ":!~", ":&", ":|", ":^", ":~", ":**", ":>>", ":<<", ":%", ":[]", ":[]?",
      ":[]=", ":<=>", ":==="].each do |symbol|
       value = symbol[1, symbol.size - 1]
-      value = value[1, value.size - 2] if value.starts_with?("\"")
+      value = value[1, value.size - 2] if value.starts_with?('"')
       it_parses symbol, value.symbol
     end
     it_parses ":foo", "foo".symbol

src/compiler/crystal/syntax/lexer.cr

@@ -555,21 +555,21 @@ module Crystal
             when '\\'
               case char = next_char
               when 'a'
-                io << "\u{7}"
+                io << '\a'
               when 'b'
-                io << "\u{8}"
+                io << '\b'
               when 'n'
-                io << "\n"
+                io << '\n'
               when 'r'
-                io << "\r"
+                io << '\r'
               when 't'
-                io << "\t"
+                io << '\t'
               when 'v'
-                io << "\v"
+                io << '\v'
               when 'f'
-                io << "\f"
+                io << '\f'
               when 'e'
-                io << "\e"
+                io << '\e'
               when 'x'
                 io.write_byte consume_string_hex_escape
               when 'u'
@@ -578,7 +578,7 @@ module Crystal
                 io.write_byte consume_octal_escape(char)
               when '\n'
                 incr_line_number nil
-                io << "\n"
+                io << '\n'
               when '\0'
                 raise "unterminated quoted symbol", line, column
               else
@@ -1928,9 +1928,9 @@ module Crystal
           else
             case char = next_char
             when 'a'
-              string_token_escape_value "\u{7}"
+              string_token_escape_value "\a"
             when 'b'
-              string_token_escape_value "\u{8}"
+              string_token_escape_value "\b"
             when 'n'
               string_token_escape_value "\n"
             when 'r'

src/compiler/crystal/tools/doc/macro.cr

@@ -29,7 +29,7 @@ class Crystal::Doc::Macro
 
   def id
     String.build do |io|
-      io << to_s.gsub(/<.+?>/, "").gsub(' ', "")
+      io << to_s.gsub(/<.+?>/, "").delete(' ')
       io << "-macro"
     end
   end
@@ -39,7 +39,7 @@ class Crystal::Doc::Macro
   end
 
   def anchor
-    "#" + URI.escape(id)
+    '#' + URI.escape(id)
   end
 
   def prefix

src/compiler/crystal/tools/doc/method.cr

@@ -88,7 +88,7 @@ class Crystal::Doc::Method
 
   def id
     String.build do |io|
-      io << to_s.gsub(/<.+?>/, "").gsub(' ', "")
+      io << to_s.gsub(/<.+?>/, "").delete(' ')
       if @class_method
         io << "-class-method"
       else

src/string.cr

@@ -3867,7 +3867,7 @@ class String
         printed_bytesize += part.bytesize
         if printed_bytesize != bytesize
           printed_bytesize += 1 # == "\n".bytesize
-          pp.text("\"")
+          pp.text('"')
           pp.text(part.inspect_unquoted)
           pp.text("\\n\"")
           break if printed_bytesize == bytesize

src/uri/punycode.cr

@@ -155,7 +155,7 @@ class URI
         first = true
         string.split('.') do |part|
           unless first
-            io << "."
+            io << '.'
           end
 
           if part.ascii_only?