Block Strings (#463)

* Block strings lexer changes * Block string parser, without indentation handling * Handle block string processing, add tests * Working indentation rules * Add typespecs * Use `re:split/3` vs `string:split/3` to support Erlang/OTP 19. * Add `prefix` as a light OTP 19 replacement for OTP 20 `string:prefix/2`. * Use `Access.key/2` vs `Access.key/1` * Add CHANGELOG entry
absinthe-graphql · Dec 5, 2017 · 53c9831 · 53c9831
1 parent 6f59497
commit 53c9831
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -1,5 +1,9 @@
 # Changelog
 
+## v1.4.5
+
+- Feature: Support for `"""`-quoted block strings, as defined in the GraphQL Specification (See facebook/graphql#397).
+
 ## v1.4.4
 
 - Bug Fix: fix where self referential interface type would cause infinite loop when introspecting.

diff --git a/src/absinthe_lexer.xrl b/src/absinthe_lexer.xrl
@@ -31,6 +31,11 @@ ExponentIndicator   = [eE]
 ExponentPart        = {ExponentIndicator}{Sign}?{Digit}+
 FloatValue          = {IntegerPart}{FractionalPart}|{IntegerPart}{ExponentPart}|{IntegerPart}{FractionalPart}{ExponentPart}
 
+% Block String Value
+EscapedBlockStringQuote = (\\""")
+BlockStringCharacter    = (\n|\t|\r|[^\x{0000}-\x{001F}]|{EscapedBlockStringQuote})
+BlockStringValue        = """{BlockStringCharacter}*"""
+
 % String Value
 HexDigit            = [0-9A-Fa-f]
 EscapedUnicode      = u{HexDigit}{HexDigit}{HexDigit}{HexDigit}
@@ -41,7 +46,6 @@ StringValue         = "{StringCharacter}*"
 % Boolean Value
 BooleanValue        = true|false
 
-
 % Reserved words
 ReservedWord        = query|mutation|subscription|fragment|on|implements|interface|union|scalar|enum|input|extend|type|directive|ON|null|schema
 
@@ -52,6 +56,7 @@ Rules.
 {ReservedWord}      : {token, {list_to_atom(TokenChars), TokenLine}}.
 {IntValue}          : {token, {int_value, TokenLine, TokenChars}}.
 {FloatValue}        : {token, {float_value, TokenLine, TokenChars}}.
+{BlockStringValue}  : {token, {block_string_value, TokenLine, TokenChars}}.
 {StringValue}       : {token, {string_value, TokenLine, TokenChars}}.
 {BooleanValue}      : {token, {boolean_value, TokenLine, TokenChars}}.
 {Name}              : {token, {name, TokenLine, TokenChars}}.

diff --git a/src/absinthe_parser.yrl b/src/absinthe_parser.yrl
@@ -19,7 +19,7 @@ Terminals
   '{' '}' '(' ')' '[' ']' '!' ':' '@' '$' '=' '|' '...'
   'query' 'mutation' 'subscription' 'fragment' 'on' 'directive'
   'type' 'implements' 'interface' 'union' 'scalar' 'enum' 'input' 'extend' 'schema'
-  name int_value float_value string_value boolean_value null.
+  name int_value float_value string_value block_string_value boolean_value null.
 
 Rootsymbol Document.
 
@@ -141,6 +141,7 @@ Name -> 'on' : extract_binary('$1').
 Value -> Variable : '$1'.
 Value -> int_value :     build_ast_node('IntValue',     #{'value' => extract_integer('$1')},             #{'start_line' => extract_line('$1')}).
 Value -> float_value :   build_ast_node('FloatValue',   #{'value' => extract_float('$1')},               #{'start_line' => extract_line('$1')}).
+Value -> block_string_value :  build_ast_node('StringValue',  #{'value' => extract_quoted_block_string_token('$1')}, #{'start_line' => extract_line('$1')}).
 Value -> string_value :  build_ast_node('StringValue',  #{'value' => extract_quoted_string_token('$1')}, #{'start_line' => extract_line('$1')}).
 Value -> boolean_value : build_ast_node('BooleanValue', #{'value' => extract_boolean('$1')},             #{'start_line' => extract_line('$1')}).
 Value -> null :          build_ast_node('NullValue',    #{},                 #{'start_line' => extract_line('$1')}).
@@ -260,46 +261,197 @@ TypeExtensionDefinition -> 'extend' ObjectTypeDefinition :
 
 Erlang code.
 
-extract_atom({Value, _Line}) -> Value.
-extract_binary(Value) when is_binary(Value) -> Value;
-extract_binary({Token, _Line}) -> list_to_binary(atom_to_list(Token));
-extract_binary({_Token, _Line, Value}) -> list_to_binary(Value).
-extract_quoted_string_token({_Token, _Line, Value}) -> iolist_to_binary(unescape(lists:sublist(Value, 2, length(Value) - 2))).
+% Line-Level Utilities
 
-unescape(Escaped) -> unescape(Escaped, []).
-
-unescape([], Acc) -> lists:reverse(Acc);
-unescape([$\\, $" | T], Acc) -> unescape(T, [$" | Acc]);
-unescape([$\\, $\\ | T], Acc) -> unescape(T, [$\\ | Acc]);
-unescape([$\\, $/ | T], Acc) -> unescape(T, [$/ | Acc]);
-unescape([$\\, $b | T], Acc) -> unescape(T, [$\b | Acc]);
-unescape([$\\, $f | T], Acc) -> unescape(T, [$\f | Acc]);
-unescape([$\\, $n | T], Acc) -> unescape(T, [$\n | Acc]);
-unescape([$\\, $r | T], Acc) -> unescape(T, [$\r | Acc]);
-unescape([$\\, $t | T], Acc) -> unescape(T, [$\t | Acc]);
-unescape([$\\, $u, A, B, C, D | T], Acc) -> unescape(T, [hexlist_to_utf8_binary([A, B, C, D]) | Acc]);
-unescape([H | T], Acc) -> unescape(T, [H | Acc]).
-
-hexlist_to_utf8_binary(HexList) -> unicode:characters_to_binary([httpd_util:hexlist_to_integer(HexList)]).
-
-extract_integer({_Token, _Line, Value}) ->
-  {Int, []} = string:to_integer(Value), Int.
-extract_float({_Token, _Line, Value}) ->
-  {Float, []} = string:to_float(Value), Float.
-extract_boolean({_Token, _Line, "true"}) -> true;
-extract_boolean({_Token, _Line, "false"}) -> false.
-extract_line({_Token, Line}) -> Line;
-extract_line({_Token, Line, _Value}) -> Line;
-extract_line(_) -> nil.
+extract_line({_Token, Line}) ->
+  Line;
+extract_line({_Token, Line, _Value}) ->
+  Line;
+extract_line(_) ->
+  nil.
 
 extract_child_line([Head|_]) ->
-    extract_child_line(Head);
+  extract_child_line(Head);
 extract_child_line(#{loc := #{'start_line' := Line}}) ->
-    Line;
+  Line;
 extract_child_line(_) ->
-    nil.
+  nil.
+
+
+% Value-level Utilities
+
+extract_atom({Value, _Line}) ->
+  Value.
+
+extract_binary(Value) when is_binary(Value) ->
+  Value;
+
+extract_binary({Token, _Line}) ->
+  list_to_binary(atom_to_list(Token));
+
+extract_binary({_Token, _Line, Value}) ->
+  list_to_binary(Value).
+
+
+% AST Generation
 
 build_ast_node(Type, Node, #{'start_line' := nil}) ->
   build_ast_node(Type, Node, nil);
 build_ast_node(Type, Node, Loc) ->
   'Elixir.Kernel':struct(list_to_atom("Elixir.Absinthe.Language." ++ atom_to_list(Type)), Node#{loc => Loc}).
+
+
+% String
+
+extract_quoted_string_token({_Token, _Line, Value}) ->
+  iolist_to_binary(process_string(lists:sublist(Value, 2, length(Value) - 2))).
+
+process_string(Escaped) ->
+  process_string(Escaped, []).
+
+process_string([], Acc) ->
+  lists:reverse(Acc);
+process_string([$\\, $" | T], Acc) ->
+  process_string(T, [$" | Acc]);
+process_string([$\\, $\\ | T], Acc) ->
+  process_string(T, [$\\ | Acc]);
+process_string([$\\, $/ | T], Acc) ->
+  process_string(T, [$/ | Acc]);
+process_string([$\\, $b | T], Acc) ->
+  process_string(T, [$\b | Acc]);
+process_string([$\\, $f | T], Acc) ->
+  process_string(T, [$\f | Acc]);
+process_string([$\\, $n | T], Acc) ->
+  process_string(T, [$\n | Acc]);
+process_string([$\\, $r | T], Acc) ->
+  process_string(T, [$\r | Acc]);
+process_string([$\\, $t | T], Acc) ->
+  process_string(T, [$\t | Acc]);
+process_string([$\\, $u, A, B, C, D | T], Acc) ->
+  process_string(T, [hexlist_to_utf8_binary([A, B, C, D]) | Acc]);
+process_string([H | T], Acc) ->
+  process_string(T, [H | Acc]).
+
+hexlist_to_utf8_binary(HexList) ->
+  unicode:characters_to_binary([httpd_util:hexlist_to_integer(HexList)]).
+
+
+% Block String
+
+extract_quoted_block_string_token({_Token, _Line, Value}) ->
+  iolist_to_binary(process_block_string(lists:sublist(Value, 4, length(Value) - 6))).
+
+-spec process_block_string(string()) -> string().
+process_block_string(Escaped) ->
+  process_block_string(Escaped, []).
+
+-spec process_block_string(string(), string()) -> string().
+process_block_string([], Acc) ->
+  block_string_value(lists:reverse(Acc));
+process_block_string([$\r, $\n | T], Acc) -> process_block_string(T, [$\n | Acc]);
+process_block_string([$\\, $", $", $" | T], Acc) -> process_block_string(T, [$", $", $"] ++ Acc);
+process_block_string([H | T], Acc) -> process_block_string(T, [H | Acc]).
+
+-spec block_string_value(string()) -> string().
+block_string_value(Value) ->
+  [FirstLine | Rest] = re:split(Value, "\n", [{return,list}]),
+  Prefix = indentation_prefix(common_indent(Rest)),
+  UnindentedLines = unindent(Rest, Prefix),
+  Lines = trim_blank_lines([FirstLine | UnindentedLines]),
+  string:join(Lines, "\n").
+
+-spec trim_blank_lines([string()]) -> [string()].
+trim_blank_lines(Lines) ->
+  trim_blank_lines(trim_blank_lines(Lines, leading), trailing).
+
+-spec trim_blank_lines([string()], leading | trailing) -> [string()].
+trim_blank_lines(Lines, leading) ->
+  lists:dropwhile(fun is_blank/1, Lines);
+trim_blank_lines(Lines, trailing) ->
+  lists:reverse(trim_blank_lines(lists:reverse(Lines), leading)).
+
+-spec indentation_prefix(non_neg_integer()) -> string().
+indentation_prefix(Indent) ->
+  lists:map(fun(_) -> 32 end, lists:seq(1, Indent)).
+
+-spec unindent([string()], string()) -> [string()].
+unindent(Lines, Prefix) ->
+  unindent(Lines, Prefix, []).
+
+-spec unindent([string()], string(), [string()]) -> [string()].
+unindent([], _Prefix, Result) ->
+  lists:reverse(Result);
+unindent([H | T], Prefix, Result) ->
+  Processed = prefix(H, Prefix),
+  unindent(T, Prefix, [Processed | Result]).
+
+-spec prefix(string(), string()) -> string().
+prefix(Line, []) ->
+  Line;
+prefix(Line, Prefix) ->
+  Prefixed = lists:prefix(Prefix, Line),
+  if
+    Prefixed ->
+      string:substr(Line, length(Prefix) + 1);
+    true ->
+      Line
+  end.
+
+-spec common_indent([string()]) -> non_neg_integer().
+common_indent(Lines) ->
+  case common_indent(Lines, noindent) of
+    noindent ->
+      0;
+    Indent ->
+      Indent
+  end.
+
+-spec common_indent([string()], noindent | non_neg_integer()) -> noindent | non_neg_integer().
+common_indent([], Indent) ->
+    Indent;
+common_indent([H | T], Indent) ->
+  CurrentIndent = leading_whitespace(H),
+  if
+    (CurrentIndent < length(H)) and ((Indent == noindent) or (CurrentIndent < Indent)) ->
+      common_indent(T, CurrentIndent);
+    true ->
+      common_indent(T, Indent)
+  end.
+
+-spec leading_whitespace(string()) -> non_neg_integer().
+leading_whitespace(BlockStringValue) ->
+  leading_whitespace(BlockStringValue, 0).
+
+-spec leading_whitespace(string(), non_neg_integer()) -> non_neg_integer().
+leading_whitespace([], N) ->
+  N;
+leading_whitespace([32 | T], N) ->
+  leading_whitespace(T, N + 1);
+leading_whitespace([$\t | T], N) ->
+  leading_whitespace(T, N + 1);
+leading_whitespace([_H | _T], N) ->
+  N.
+
+-spec is_blank(string()) -> boolean().
+is_blank(BlockStringValue) ->
+    leading_whitespace(BlockStringValue) == length(BlockStringValue).
+
+
+% Integer
+
+extract_integer({_Token, _Line, Value}) ->
+  {Int, []} = string:to_integer(Value), Int.
+
+
+% Float
+
+extract_float({_Token, _Line, Value}) ->
+  {Float, []} = string:to_float(Value), Float.
+
+
+% Boolean
+
+extract_boolean({_Token, _Line, "true"}) ->
+  true;
+extract_boolean({_Token, _Line, "false"}) ->
+  false.