Support block string syntax

lib/graphql/compatibility/query_parser_specification.rb

@@ -67,6 +67,10 @@ def test_it_parses_inputs
                   nullValue: null
                   nullValueInObject: {a: null, b: "b"}
                   nullValueInArray: ["a", null, "b"]
+                  blockString: """
+                  Hello,
+                    World
+                  """
                 )
               }
             |
@@ -100,6 +104,9 @@ def test_it_parses_inputs
             assert_equal 'a', values[0]
             assert_instance_of GraphQL::Language::Nodes::NullValue, values[1]
             assert_equal 'b', values[2]
+
+            block_str_value = inputs[12].value
+            assert_equal "Hello,\n  World", block_str_value
           end
 
           def test_it_doesnt_parse_nonsense_variables

lib/graphql/language.rb

@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+require "graphql/language/block_string"
 require "graphql/language/printer"
 require "graphql/language/definition_slice"
 require "graphql/language/document_from_schema_definition"

lib/graphql/language/block_string.rb

@@ -0,0 +1,47 @@
+# frozen_string_literal: true
+module GraphQL
+  module Language
+    module BlockString
+      # Remove leading and trailing whitespace from a block string.
+      # See "Block Strings" in https://github.com/facebook/graphql/blob/master/spec/Section%202%20--%20Language.md
+      def self.trim_whitespace(str)
+        lines = str.split("\n")
+        common_indent = nil
+
+        # find the common whitespace
+        lines.each_with_index do |line, idx|
+          if idx == 0
+            next
+          end
+          line_length = line.size
+          line_indent = line[/\A */].size
+          if line_indent < line_length && (common_indent.nil? || line_indent < common_indent)
+            common_indent = line_indent
+          end
+        end
+
+        # Remove the common whitespace
+        if common_indent
+          lines.each_with_index do |line, idx|
+            if idx == 0
+              next
+            else
+              line[0, common_indent] = ""
+            end
+          end
+        end
+
+        # Remove leading & trailing blank lines
+        while lines.first.empty?
+          lines.shift
+        end
+        while lines.last.empty?
+          lines.pop
+        end
+
+        # Rebuild the string
+        lines.join("\n")
+      end
+    end
+  end
+end

lib/graphql/language/lexer.rl

@@ -34,6 +34,9 @@
   RBRACKET =      ']';
   COLON =         ':';
   QUOTE =         '"';
+  BLOCK_QUOTE =   '"""';
+  ESCAPED_BLOCK_QUOTE = '\\"""';
+  BLOCK_STRING_CHAR = (ESCAPED_BLOCK_QUOTE | ^'"""');
   ESCAPED_QUOTE = '\\"';
   STRING_CHAR =   (ESCAPED_QUOTE | ^'"');
   VAR_SIGN =      '$';
@@ -44,7 +47,7 @@
   PIPE =          '|';
 
   QUOTED_STRING = QUOTE STRING_CHAR* QUOTE;
-
+  BLOCK_STRING = BLOCK_QUOTE BLOCK_STRING_CHAR* BLOCK_QUOTE;
   # catch-all for anything else. must be at the bottom for precedence.
   UNKNOWN_CHAR =         /./;
 
@@ -75,7 +78,8 @@
     RBRACKET      => { emit(:RBRACKET, ts, te, meta) };
     LBRACKET      => { emit(:LBRACKET, ts, te, meta) };
     COLON         => { emit(:COLON, ts, te, meta) };
-    QUOTED_STRING => { emit_string(ts + 1, te, meta) };
+    QUOTED_STRING => { emit_string(ts, te, meta, block: false) };
+    BLOCK_STRING  => { emit_string(ts, te, meta, block: true) };
     VAR_SIGN      => { emit(:VAR_SIGN, ts, te, meta) };
     DIR_SIGN      => { emit(:DIR_SIGN, ts, te, meta) };
     ELLIPSIS      => { emit(:ELLIPSIS, ts, te, meta) };
@@ -188,8 +192,13 @@ module GraphQL
       PACK_DIRECTIVE = "c*"
       UTF_8_ENCODING = "UTF-8"
 
-      def self.emit_string(ts, te, meta)
-        value = meta[:data][ts...te - 1].pack(PACK_DIRECTIVE).force_encoding(UTF_8_ENCODING)
+      def self.emit_string(ts, te, meta, block:)
+        quotes_length = block ? 3 : 1
+        ts += quotes_length
+        value = meta[:data][ts...te - quotes_length].pack(PACK_DIRECTIVE).force_encoding(UTF_8_ENCODING)
+        if block
+          value = GraphQL::Language::BlockString.trim_whitespace(value)
+        end
         if value !~ VALID_STRING
           meta[:tokens] << token = GraphQL::Language::Token.new(
             name: :BAD_UNICODE_ESCAPE,

spec/graphql/directive_spec.rb

@@ -31,7 +31,9 @@
     describe "child fields" do
       let(:query_string) { <<-GRAPHQL
       {
-        __type(name: "Cheese") {
+        __type(name: """
+        Cheese
+        """) {
           fields { name }
           fields @skip(if: true) { isDeprecated }
         }

spec/graphql/language/block_string_spec.rb

@@ -0,0 +1,70 @@
+# frozen_string_literal: true
+require "spec_helper"
+
+describe GraphQL::Language::BlockString do
+  describe "trimming whitespace" do
+    def trim_whitespace(str)
+      GraphQL::Language::BlockString.trim_whitespace(str)
+    end
+
+    it "matches the examples in graphql-js" do
+      # these are taken from:
+      # https://github.com/graphql/graphql-js/blob/36ec0e9d34666362ff0e2b2b18edeb98e3c9abee/src/language/__tests__/blockStringValue-test.js#L12
+      # A set of [before, after] pairs:
+      examples = [
+        [
+          # Removes common whitespace:
+          "
+          Hello,
+            World!
+
+          Yours,
+            GraphQL.
+          ",
+          "Hello,\n  World!\n\nYours,\n  GraphQL."
+        ],
+        [
+          # Removes leading and trailing newlines:
+          "
+
+          Hello,
+            World!
+
+          Yours,
+            GraphQL.
+
+          ",
+          "Hello,\n  World!\n\nYours,\n  GraphQL."
+        ],
+        [
+          # Removes blank lines (with whitespace _and_ newlines:)
+          "\n    \n
+          Hello,
+            World!
+
+          Yours,
+            GraphQL.
+
+          \n     \n",
+          "Hello,\n  World!\n\nYours,\n  GraphQL."
+        ],
+        [
+          # Retains indentation from the first line
+          "    Hello,\n      World!\n\n    Yours,\n      GraphQL.",
+          "    Hello,\n  World!\n\nYours,\n  GraphQL.",
+        ],
+        [
+          # Doesn't alter trailing spaces
+          "\n    \n    Hello,     \n      World!   \n\n    Yours,     \n      GraphQL.  ",
+          "Hello,     \n  World!   \n\nYours,     \n  GraphQL.  ",
+
+        ],
+      ]
+
+      examples.each_with_index do |(before, after), idx|
+        transformed_str = trim_whitespace(before)
+        assert_equal(after, transformed_str, "Example ##{idx + 1}")
+      end
+    end
+  end
+end

spec/graphql/language/lexer_spec.rb

@@ -26,6 +26,15 @@
       assert_equal tokens[0], tokens[1].prev_token
     end
 
+    describe "block strings" do
+      let(:query_string) { %|{ a(b: """\nc\n  d\n""")}|}
+
+      it "tokenizes them" do
+        str_token = tokens[5]
+        assert_equal "c\n  d", str_token.value
+      end
+    end
+
     it "unescapes escaped characters" do
       assert_equal "\" \\ / \b \f \n \r \t", subject.tokenize('"\\" \\\\ \\/ \\b \\f \\n \\r \\t"').first.to_s
     end

spec/graphql/query_spec.rb

@@ -85,7 +85,7 @@
         operation_name: operation_name,
         max_depth: max_depth,
       )
-      query.query_string = '{ __type(name: "Cheese") { name } }'
+      query.query_string = '{ __type(name: """Cheese""") { name } }'
       assert_equal "Cheese", query.result["data"] ["__type"]["name"]
     end
   end