* Refactoring: put the Nix expression evaluator in its own library so

  that it can be used by multiple programs.

1 files changed, 209 insertions, 0 deletions

diff --git a/src/libexpr/nix.sdf b/src/libexpr/nix.sdf
new file mode 100644
index 000000000..615bdb974
--- /dev/null
+++ b/src/libexpr/nix.sdf
@@ -0,0 +1,209 @@
+definition
+
+module Main
+imports Fix
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% Top level syntax.
+
+module Fix
+imports Fix-Exprs Fix-Layout
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% Expressions.
+
+module Fix-Exprs
+imports Fix-Lexicals URI
+exports
+  sorts Expr Formal Bind Binds BindSemi ExprList
+  context-free syntax
+
+    Id -> Expr {cons("Var")}
+
+    Int -> Expr {cons("Int")}
+
+    Str -> Expr {cons("Str")}
+
+    Uri -> Expr {cons("Uri")}
+
+    Path -> Expr {cons("Path")}
+
+    "(" Expr ")" -> Expr {bracket}
+
+    Expr Expr -> Expr {cons("Call"), left}
+
+    "{" {Formal ","}* "}" ":" Expr -> Expr {cons("Function")}
+    Id -> Formal {cons("NoDefFormal")}
+    Id "?" Expr -> Formal {cons("DefFormal")}
+
+    "assert" Expr ";" Expr -> Expr {cons("Assert")}
+
+    "rec" "{" Binds "}" -> Expr {cons("Rec")}
+    "let" "{" Binds "}" -> Expr {cons("LetRec")}
+    "{" Binds "}" -> Expr {cons("Attrs")}
+
+    Id "=" Expr -> Bind {cons("Bind")}
+    {Bind ";"}* -> Binds
+    Bind ";" -> BindSemi 
+    BindSemi* -> Binds
+
+    "[" ExprList "]" -> Expr {cons("List")}
+    "" -> ExprList {cons("ExprNil")}
+    Expr ExprList -> ExprList {cons("ExprCons")}
+
+    Expr "." Id -> Expr {cons("Select")}
+
+    "if" Expr "then" Expr "else" Expr -> Expr {cons("If")}
+
+    Expr "==" Expr -> Expr {cons("OpEq"), non-assoc}
+    Expr "!=" Expr -> Expr {cons("OpNEq"), non-assoc}
+
+    "!" Expr -> Expr {cons("OpNot")}
+    Expr "&&" Expr -> Expr {cons("OpAnd"), right}
+    Expr "||" Expr -> Expr {cons("OpOr"), right}
+    Expr "->" Expr -> Expr {cons("OpImpl"), right}
+
+    Bool -> Expr {cons("Bool")}
+
+  context-free priorities
+
+    Expr "." Id -> Expr
+  > Expr ExprList -> ExprList
+  > Expr Expr -> Expr
+  > "!" Expr -> Expr
+  > Expr "==" Expr -> Expr
+  > Expr "!=" Expr -> Expr
+  > Expr "&&" Expr -> Expr
+  > Expr "||" Expr -> Expr
+  > Expr "->" Expr -> Expr
+  > "assert" Expr ";" Expr -> Expr
+  > "{" {Formal ","}* "}" ":" Expr -> Expr
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% Lexical syntax.
+
+module Fix-Lexicals
+exports
+  sorts Id Int Str Path PathComp Bool
+  lexical syntax
+    [a-zA-Z\_][a-zA-Z0-9\_\']* -> Id
+    "rec" -> Id {reject}
+    "let" -> Id {reject}
+    "if" -> Id {reject}
+    "then" -> Id {reject}
+    "else" -> Id {reject}
+    "true" -> Id {reject}
+    "false" -> Id {reject}
+    "assert" -> Id {reject}
+
+    [0-9]+ -> Int
+
+    "\"" ~[\n\"]* "\"" -> Str
+
+    PathComp ("/" PathComp)+ -> Path
+    [a-zA-Z0-9\.\_\-\+]+ -> PathComp
+
+    "true" -> Bool
+    "false" -> Bool
+
+  lexical restrictions
+    Id -/- [a-zA-Z0-9\_\']
+    Int -/- [0-9]
+    Path -/- [a-zA-Z0-9\.\_\-\+\/]
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% URIs (RFC 2396, appendix A).
+
+module URI
+exports
+  sorts Uri Uhierpart Uopaquepart Uuricnoslash Unetpath Uabspath
+        Urelpath Urelsegment Uscheme Uauthority Uregname Userver
+        Uuserinfo Uhostport Uhost Uhostname Udomainlabel Utoplabel
+        UIPv4address Uport Upath Upathsegments Usegment Uparam
+        Upchar Uquery Ufragment Uuric Ureserved Uunreserved Umark
+        Uescaped Uhex Ualphanum Ualpha Ulowalpha Uupalpha Udigit
+  lexical syntax
+    Uscheme ":" (Uhierpart | Uopaquepart) -> Uri
+
+    (Unetpath | Uabspath) ("?" Uquery)? -> Uhierpart
+    Uuricnoslash Uuric* -> Uopaquepart
+
+    Uunreserved | Uescaped | [\;\?\:\@\&\=\+\$\,] -> Uuricnoslash
+
+    "//" Uauthority Uabspath? -> Unetpath
+    "/" Upathsegments -> Uabspath
+    "//" Uuric* -> Uabspath {reject}
+    Urelsegment Uabspath? -> Urelpath
+
+    (Uunreserved | Uescaped | [\;\@\&\=\+\$\,])+ -> Urelsegment
+
+    Ualpha (Ualpha | Udigit | [\+\-\.])* -> Uscheme
+
+    Userver | Uregname -> Uauthority
+
+    (Uunreserved | Uescaped | [\$\,\;\:\@\&\=\+])+ -> Uregname
+
+    ((Uuserinfo "@") Uhostport) -> Userver
+    (Uunreserved | Uescaped | [\;\:\&\=\+\$\,])* -> Uuserinfo
+
+    Uhost (":" Uport)? -> Uhostport
+    Uhostname | UIPv4address -> Uhost
+    (Udomainlabel ".")+ Utoplabel "."? -> Uhostname
+    Ualphanum | Ualphanum (Ualphanum | "-")* Ualphanum -> Udomainlabel
+    Ualpha | Ualpha (Ualphanum | "-")* Ualphanum -> Utoplabel
+    Udigit+ "." Udigit+ "." Udigit+ "." Udigit+ -> UIPv4address
+    Udigit* -> Uport
+
+    Uabspath | Uopaquepart -> Upath
+    Usegment ("/" Usegment)* -> Upathsegments
+    Upchar* (";" Uparam)* -> Usegment
+    Upchar* -> Uparam
+    Uunreserved | Uescaped | [\:\@\&\=\+\$\,] -> Upchar
+
+    Uuric* -> Uquery
+
+    Uuric* -> Ufragment
+
+    Ureserved | Uunreserved | Uescaped -> Uuric
+    [\;\/\?\:\@\&\=\+\$\,] -> Ureserved
+    Ualphanum | Umark -> Uunreserved
+    [\-\_\.\!\~\*\'\(\)] -> Umark
+
+    "%" Uhex Uhex -> Uescaped
+    Udigit | [A-Fa-f] -> Uhex
+
+    Ualpha | Udigit -> Ualphanum
+    Ulowalpha | Uupalpha -> Ualpha
+
+    [a-z] -> Ulowalpha
+    [A-Z] -> Uupalpha
+    [0-9] -> Udigit
+
+  lexical restrictions
+    Uri -/- [a-zA-Z0-9\-\_\.\!\~\*\'\(\)]
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% Layout.
+
+module Fix-Layout
+exports
+  sorts HashComment Asterisk Comment EOF
+  lexical syntax
+    [\ \t\n] -> LAYOUT
+    HashComment -> LAYOUT
+    Comment -> LAYOUT
+    "#" ~[\n]* ([\n] | EOF) -> HashComment
+    "//" ~[\n]* ([\n] | EOF) -> HashComment
+    "/*" ( ~[\*] | Asterisk )* "*/" -> Comment
+    [\*] -> Asterisk
+    "" -> EOF
+  lexical restrictions
+    Asterisk -/- [\/]
+    EOF -/- ~[]
+  context-free restrictions
+    LAYOUT? -/- [\ \t\n] | [\#]