Added the missing \b escape sequence in chars and strings

spec/compiler/lexer/lexer_spec.cr

@@ -186,6 +186,7 @@ describe "Lexer" do
   it_lexes_u64 ["9223372036854775808", "-9223372036854775809"]
 
   it_lexes_char "'a'", 'a'
+  it_lexes_char "'\\b'", 8.chr
   it_lexes_char "'\\n'", '\n'
   it_lexes_char "'\\t'", '\t'
   it_lexes_char "'\\v'", '\v'

spec/std/char_spec.cr

@@ -45,6 +45,7 @@ describe "Char" do
   end
 
   it "escapes" do
+    # TODO '\b'.ord.should eq(8)
     '\t'.ord.should eq(9)
     '\n'.ord.should eq(10)
     '\v'.ord.should eq(11)

spec/std/json/serialization_spec.cr

@@ -75,7 +75,7 @@ describe "Json serialization" do
     end
 
     it "does for String with control codes" do
-      "\b".to_json.should eq("\"\\b\"")
+      # TODO "\b".to_json.should eq("\"\\b\"")
       "\f".to_json.should eq("\"\\f\"")
       "\n".to_json.should eq("\"\\n\"")
       "\r".to_json.should eq("\"\\r\"")

spec/std/string_spec.cr

@@ -409,6 +409,7 @@ describe "String" do
     "a".dump.should eq("\"a\"")
     "\\".dump.should eq("\"\\\\\"")
     "\"".dump.should eq("\"\\\"\"")
+    # TODO "\b".dump.should eq("\"\\b\"")
     "\e".dump.should eq("\"\\e\"")
     "\f".dump.should eq("\"\\f\"")
     "\n".dump.should eq("\"\\n\"")
@@ -424,6 +425,7 @@ describe "String" do
     "a".inspect.should eq("\"a\"")
     "\\".inspect.should eq("\"\\\\\"")
     "\"".inspect.should eq("\"\\\"\"")
+    # TODO "\b".inspect.should eq("\"\\b\"")
     "\e".inspect.should eq("\"\\e\"")
     "\f".inspect.should eq("\"\\f\"")
     "\n".inspect.should eq("\"\\n\"")
@@ -486,6 +488,7 @@ describe "String" do
   end
 
   it "escapes chars" do
+    # TODO "\b"[0].should eq('\b')
     "\t"[0].should eq('\t')
     "\n"[0].should eq('\n')
     "\v"[0].should eq('\v')

src/compiler/crystal/syntax/lexer.cr

@@ -402,6 +402,8 @@ module Crystal
         case char1 = next_char
         when '\\'
           case char2 = next_char
+          when 'b'
+            @token.value = 8.chr # TODO use \b
           when 'e'
             @token.value = '\e'
           when 'f'
@@ -1375,6 +1377,8 @@ module Crystal
           @token.value = "\\#{char}"
         else
           case char = next_char
+          when 'b'
+            string_token_escape_value "\u{8}"
           when 'n'
             string_token_escape_value "\n"
           when 'r'

src/json/to_json.cr

@@ -88,7 +88,7 @@ class String
         io << "\\\\"
       when '"'
         io << "\\\""
-      when '\b'
+      when 8.chr # TODO use '\b'
         io << "\\b"
       when '\f'
         io << "\\f"

src/string.cr

@@ -775,6 +775,7 @@ class String
       case current_char
       when '"'  then io << "\\\""
       when '\\' then io << "\\\\"
+      when (8.chr) then io << "\\b" # TODO use \b in when
       when '\e' then io << "\\e"
       when '\f' then io << "\\f"
       when '\n' then io << "\\n"