Whitespace

1 files changed, 15 insertions, 17 deletions

diff --git a/dhall_parser/src/dhall.abnf b/dhall_parser/src/dhall.abnf
index 52d5b91..9456036 100644
--- a/dhall_parser/src/dhall.abnf
+++ b/dhall_parser/src/dhall.abnf
@@ -620,7 +620,8 @@ selector = any-label / labels
 

 labels = "{" whsp [ any-label whsp *("," whsp any-label whsp) ] "}"

 

-

+; NOTE: Backtrack when parsing the first three alternatives (i.e. the numeric

+; literals).  This is because they share leading characters in common

 primitive-expression =

     ; "2.0"

       double-literal

@@ -634,27 +635,27 @@ primitive-expression =
     ; '"ABC"'

     / text-literal

     

+    / "{" whsp record-type-or-literal whsp "}"

+    / "<" whsp union-type-or-literal whsp ">"

+    / non-empty-list-literal

     ; "x"

     ; "x@2"

     / identifier

-    / "{" whsp record-type-or-literal "}"

-    / "<" whsp union-type-or-literal ">"

-    / non-empty-list-literal

-    / parenthesized-expression

+    / "(" whsp expression whsp ")"

 

 record-type-or-literal =

       empty-record-literal

     / non-empty-record-type-or-literal

     / empty-record-type

-empty-record-literal = "=" whsp

+empty-record-literal = "="

 empty-record-type = ""

 

 non-empty-record-type-or-literal =

     any-label whsp (non-empty-record-literal / non-empty-record-type)

-non-empty-record-type    = ":" whsp1 expression whsp *("," whsp record-type-entry)

-record-type-entry = any-label whsp ":" whsp1 expression whsp

-non-empty-record-literal = "=" whsp expression whsp *("," whsp record-literal-entry)

-record-literal-entry = any-label whsp "=" whsp expression whsp

+non-empty-record-type    = ":" whsp1 expression *(whsp "," whsp record-type-entry)

+record-type-entry = any-label whsp ":" whsp1 expression

+non-empty-record-literal = "=" whsp expression *(whsp "," whsp record-literal-entry)

+record-literal-entry = any-label whsp "=" whsp expression

 

 ; "< Foo : Integer | Bar : Bool >"

 ; "< Foo : Integer | Bar = True >"

@@ -666,19 +667,16 @@ empty-union-type = ""
 

 non-empty-union-type-or-literal =

     any-label whsp

-    ( "=" whsp expression whsp union-type-entries

-    / ":" whsp1 expression whsp [ "|" whsp non-empty-union-type-or-literal ]

+    ( "=" whsp expression union-type-entries

+    / ":" whsp1 expression [ whsp "|" whsp non-empty-union-type-or-literal ]

     )

-union-type-entries = *("|" whsp union-type-entry)

-union-type-entry = any-label whsp ":" whsp1 expression whsp

+union-type-entries = *(whsp "|" whsp union-type-entry)

+union-type-entry = any-label whsp ":" whsp1 expression

 

 ; "[1, 2, 3]"

 ; `empty-list-or-optional` handles empty lists

 non-empty-list-literal = "[" whsp expression whsp *("," whsp expression whsp) "]"

 

-; "( e )"

-parenthesized-expression = "(" whsp expression whsp ")"

-

 

 ; This just adds surrounding whitespace for the top-level of the program

 complete-expression = whsp expression whsp