diff options
Diffstat (limited to '')
| -rw-r--r-- | dhall_parser/src/dhall.abnf | 115 | ||||
| -rw-r--r-- | dhall_parser/src/dhall.pest.visibility | 5 |
2 files changed, 75 insertions, 45 deletions
diff --git a/dhall_parser/src/dhall.abnf b/dhall_parser/src/dhall.abnf index 51de689..f9ba91e 100644 --- a/dhall_parser/src/dhall.abnf +++ b/dhall_parser/src/dhall.abnf @@ -152,17 +152,34 @@ HEXDIG = DIGIT / "A" / "B" / "C" / "D" / "E" / "F" ; * as
; * using
; * merge
+; * missing
+; * Infinity
+; * Some
simple-label-first-char = ALPHA / "_"
simple-label-next-char = ALPHA / DIGIT / "-" / "/" / "_"
simple-label = simple-label-first-char *simple-label-next-char
-quoted-label = 1*(ALPHA / DIGIT / "-" / "/" / "_" / ":" / "." / "$")
+quoted-label-char =
+ %x20-5F
+ ; %x60 = '`'
+ / %x61-7E
+
+quoted-label = 1*quoted-label-char
; NOTE: Dhall does not support Unicode labels, mainly to minimize the potential
; for code obfuscation
+; A label cannot not be any of the reserved identifiers for builtins (unless quoted).
+; Their list can be found in semantics.md. This is not enforced by the grammar but
+; should be checked by implementations. The only place where this restriction applies
+; is bound variables.
label-raw = ("`" quoted-label "`" / simple-label)
label = label-raw whitespace
+; An any-label is allowed to be one of the reserved identifiers.
+any-label = label
+any-label-raw = label-raw
+
+
; Dhall's double-quoted strings are equivalent to JSON strings except with
; support for string interpolation (and escaping string interpolation)
;
@@ -266,6 +283,7 @@ text-literal-raw = (double-quote-literal / single-quote-literal) ;
; If you don't feel like reading hex, these are all the same as the rule name,
; except without the '-raw' ending.
+; Keywords that should never be parsed as identifiers
if-raw = %x69.66
then-raw = %x74.68.65.6e
else-raw = %x65.6c.73.65
@@ -275,11 +293,14 @@ as-raw = %x61.73 using-raw = %x75.73.69.6e.67
merge-raw = %x6d.65.72.67.65
missing-raw = %x6d.69.73.73.69.6e.67
+Infinity-raw = %x49.6e.66.69.6e.69.74.79
+; Reserved identifiers, only needed for some special cases of parsing
Optional-raw = %x4f.70.74.69.6f.6e.61.6c
Text-raw = %x54.65.78.74
List-raw = %x4c.69.73.74
Infinity-raw = %x49.6e.66.69.6e.69.74.79
NaN-raw = %x4e.61.4e
+Some-raw = %x53.6f.6d.65
; Whitespaced rules for reserved words, to be used when matching expressions
if = if-raw nonempty-whitespace
@@ -290,38 +311,39 @@ in = in-raw nonempty-whitespace as = as-raw nonempty-whitespace
using = using-raw nonempty-whitespace
merge = merge-raw nonempty-whitespace
+Some = Some-raw nonempty-whitespace
Optional = Optional-raw whitespace
Text = Text-raw whitespace
List = List-raw whitespace
-equal = "=" whitespace
-or = "||" whitespace
-plus = "+" nonempty-whitespace ; To disambiguate `f +2`
-text-append = "++" whitespace
-list-append = "#" whitespace
-and = "&&" whitespace
-times = "*" whitespace
-double-equal = "==" whitespace
-not-equal = "!=" whitespace
-dot = "." whitespace
-bar = "|" whitespace
-comma = "," whitespace
-at = "@" whitespace
-colon = ":" nonempty-whitespace ; To disambiguate `env:VARIABLE` from type annotations
-import-alt = "?" nonempty-whitespace ; To disambiguate `http://a/a?a`
-open-parens = "(" whitespace
+
+equal = "=" whitespace
+or = "||" whitespace
+plus = "+" nonempty-whitespace ; To disambiguate `f +2`
+text-append = "++" whitespace
+list-append = "#" whitespace
+and = "&&" whitespace
+times = "*" whitespace
+double-equal = "==" whitespace
+not-equal = "!=" whitespace
+dot = "." whitespace
+bar = "|" whitespace
+comma = "," whitespace
+at = "@" whitespace
+open-parens = "(" whitespace
close-parens-raw = ")"
-close-parens = ")" whitespace
-open-brace = "{" whitespace
+close-parens = ")" whitespace
+open-brace = "{" whitespace
close-brace-raw = "}"
-close-brace = "}" whitespace
-open-bracket = "[" whitespace
+close-brace = "}" whitespace
+open-bracket = "[" whitespace
close-bracket-raw = "]"
-close-bracket = "]" whitespace
-open-angle = "<" whitespace
+close-bracket = "]" whitespace
+open-angle = "<" whitespace
close-angle-raw = ">"
-close-angle = ">" whitespace
-
+close-angle = ">" whitespace
+colon = ":" nonempty-whitespace ; To disambiguate `env:VARIABLE` from type annotations
+import-alt = "?" nonempty-whitespace ; To disambiguate `http://a/a?a`
combine = ( %x2227 / "/\" ) whitespace
combine-types = ( %x2A53 / "//\\" ) whitespace
prefer = ( %x2AFD / "//" ) whitespace
@@ -337,7 +359,9 @@ natural-literal-raw = 1*DIGIT integer-literal-raw = ( "+" / "-" ) natural-literal-raw
-identifier-raw = label-raw [ whitespace at natural-literal-raw ]
+; The implementation should recognize reserved names for builtins and treat them as special
+; values instead of variables.
+identifier-raw = any-label-raw [ whitespace at natural-literal-raw ]
identifier = identifier-raw whitespace
; Printable characters other than " ()[]{}<>/\,"
@@ -406,8 +430,12 @@ absolute-path = path ; Absolute path scheme = %x68.74.74.70 [ %x73 ] ; "http" [ "s" ]
-; NOTE: This does not match the official grammar for a URI. Specifically, this
-; replaces `path-abempty` with `path`
+; NOTE: This does not match the official grammar for a URI. Specifically:
+;
+; * this replaces `path-abempty` with `path`, so an empty path is
+; not valid
+; * this does not support fragment identifiers, which have no meaning within
+; Dhall expressions and do not affect import resolution
http-raw = scheme "://" authority path [ "?" query ]
; NOTE: Backtrack if parsing the optional user info prefix fails
@@ -544,8 +572,6 @@ import-raw = import-hashed-raw [ whitespace as Text-raw ] ; The exception is the rules ending in -raw, which should _not_ end in whitespace.
; This is important to avoid the need for sequential backtracking in application-expression.
-; An arbitrary dhall expression. Only use in a context where parentheses or
-; keywords prevent possible ambiguity. See also atomic-expression.
expression =
lambda-expression
/ ifthenelse-expression
@@ -580,14 +606,14 @@ arrow-expression = operator-expression arrow expression ; "merge e1 e2 : t"
; "merge e1 e2"
-merge-expression = merge atomic-expression atomic-expression [ colon application-expression ]
+merge-expression = merge import-expression import-expression [ colon application-expression ]
; "[] : List t"
; "[] : Optional t"
; "[x] : Optional t"
empty-list-or-optional = open-bracket (empty-collection / non-empty-optional)
-empty-collection = close-bracket colon (List / Optional) atomic-expression
-non-empty-optional = expression close-bracket colon Optional atomic-expression
+empty-collection = close-bracket colon (List / Optional) import-expression
+non-empty-optional = expression close-bracket colon Optional import-expression
; "x : t"
annotated-expression = operator-expression [ colon expression ]
@@ -611,12 +637,11 @@ not-equal-expression = application-expression *(not-equal application- ; Import expressions need to be separated by some whitespace, otherwise there
; would be ambiguity: `./ab` could be interpreted as "import the file `./ab`",
; or "apply the import `./a` to label `b`"
-; The -raw handling is important for greedy parsers, that can't do sequential backtracking.
-application-expression = atomic-expression-raw *(nonempty-whitespace atomic-expression-raw) whitespace
+application-expression =
+ import-expression-raw *(nonempty-whitespace import-expression-raw) whitespace
-; An expression that does not need to be surrounded by parentheses to disambiguate
-atomic-expression = atomic-expression-raw whitespace
-atomic-expression-raw =
+import-expression = import-expression-raw whitespace
+import-expression-raw =
import-raw
/ selector-expression-raw
@@ -629,9 +654,9 @@ atomic-expression-raw = ; the function `foo` to the relative path `./bar`)
selector-expression-raw = primitive-expression-raw *(whitespace dot selector-raw)
-selector-raw = label-raw / labels-raw
+selector-raw = any-label-raw / labels-raw
-labels-raw = open-brace [ label *(comma label) ] close-brace-raw
+labels-raw = open-brace [ any-label *(comma any-label) ] close-brace-raw
primitive-expression-raw =
@@ -679,11 +704,11 @@ record-type-or-literal = empty-record-literal = equal
empty-record-type = ""
non-empty-record-type-or-literal =
- label (non-empty-record-literal / non-empty-record-type)
+ any-label (non-empty-record-literal / non-empty-record-type)
non-empty-record-type = colon expression *(comma record-type-entry)
-record-type-entry = label colon expression
+record-type-entry = any-label colon expression
non-empty-record-literal = equal expression *(comma record-literal-entry)
-record-literal-entry = label equal expression
+record-literal-entry = any-label equal expression
; "< Foo : Integer | Bar : Bool >"
; "< Foo : Integer | Bar = True >"
@@ -692,12 +717,12 @@ union-type-or-literal = / empty-union-type
empty-union-type = ""
non-empty-union-type-or-literal =
- label
+ any-label
( equal expression union-type-entries
/ colon expression [ bar non-empty-union-type-or-literal ]
)
union-type-entries = *(bar union-type-entry)
-union-type-entry = label colon expression
+union-type-entry = any-label colon expression
; "[1, 2, 3]"
; `empty-list-or-optional` handles empty lists
diff --git a/dhall_parser/src/dhall.pest.visibility b/dhall_parser/src/dhall.pest.visibility index 3d0a80c..da5217a 100644 --- a/dhall_parser/src/dhall.pest.visibility +++ b/dhall_parser/src/dhall.pest.visibility @@ -18,9 +18,12 @@ end_of_line # simple_label_next_char # simple_label_start simple_label +# quoted_label_char quoted_label label_raw # label +# any_label_raw +# any_label double_quote_chunk double_quote_escaped double_quote_literal @@ -151,6 +154,8 @@ not_equal_expression application_expression # atomic_expression # atomic_expression_raw +# import_expression +# import_expression_raw selector_expression_raw selector_raw labels_raw |