From 9279174dde3e1a450e63e866d2683352dd8238d3 Mon Sep 17 00:00:00 2001 From: Eelco Dolstra Date: Thu, 14 Aug 2008 14:00:44 +0000 Subject: * Added an experimental feature suggested by Andres: ellipses ("...") in attribute set pattern matches. This allows defining a function that takes *at least* the listed attributes, while ignoring additional attributes. For instance, {stdenv, fetchurl, fuse, ...}: stdenv.mkDerivation { ... }; defines a function that requires an attribute set that contains the specified attributes but ignores others. The main advantage is that we can then write in all-packages.nix aefs = import ../bla/aefs pkgs; instead of aefs = import ../bla/aefs { inherit stdenv fetchurl fuse; }; This saves a lot of typing (not to mention not having to update all-packages.nix with purely mechanical changes). It saves as much typing as the "args: with args;" style, but has the advantage that the function arguments are properly declared (not implicit in what the body of the "with" uses). --- src/libexpr/eval.cc | 12 +++++++----- src/libexpr/expr-to-xml.cc | 4 +++- src/libexpr/lexer.l | 1 + src/libexpr/nixexpr-ast.def | 8 ++++---- src/libexpr/nixexpr.cc | 5 +++-- src/libexpr/nixexpr.hh | 1 + src/libexpr/parser.y | 24 ++++++++++++++++++------ 7 files changed, 37 insertions(+), 18 deletions(-) (limited to 'src/libexpr') diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc index ebcbac5391c9..e79d42504d0a 100644 --- a/src/libexpr/eval.cc +++ b/src/libexpr/eval.cc @@ -84,11 +84,12 @@ static void patternMatch(EvalState & state, ATerm name; ATermList formals; Pattern pat1, pat2; + ATermBool ellipsis; if (matchVarPat(pat, name)) subs.set(name, arg); - else if (matchAttrsPat(pat, formals)) { + else if (matchAttrsPat(pat, formals, ellipsis)) { arg = evalExpr(state, arg); @@ -122,8 +123,8 @@ static void patternMatch(EvalState & state, } /* Check that each actual argument is listed as a formal - argument. */ - if (attrsUsed != nrAttrs) + argument (unless the attribute match specifies a `...'). */ + if (ellipsis == eFalse && attrsUsed != nrAttrs) throw TypeError(format("the function does not expect an argument named `%1%'") % aterm2String(attrs.begin()->key)); } @@ -402,9 +403,10 @@ Expr autoCallFunction(Expr e, const ATermMap & args) Pattern pat; ATerm body, pos; ATermList formals; - + ATermBool ellipsis; + /* !!! this should be more general */ - if (matchFunction(e, pat, body, pos) && matchAttrsPat(pat, formals)) { + if (matchFunction(e, pat, body, pos) && matchAttrsPat(pat, formals, ellipsis)) { ATermMap actualArgs(ATgetLength(formals)); for (ATermIterator i(formals); i; ++i) { diff --git a/src/libexpr/expr-to-xml.cc b/src/libexpr/expr-to-xml.cc index 6ec906356a68..e401001ead01 100644 --- a/src/libexpr/expr-to-xml.cc +++ b/src/libexpr/expr-to-xml.cc @@ -45,15 +45,17 @@ static void printPatternAsXML(Pattern pat, XMLWriter & doc) ATerm name; ATermList formals; Pattern pat1, pat2; + ATermBool ellipsis; if (matchVarPat(pat, name)) doc.writeEmptyElement("varpat", singletonAttrs("name", aterm2String(name))); - else if (matchAttrsPat(pat, formals)) { + else if (matchAttrsPat(pat, formals, ellipsis)) { XMLOpenElement _(doc, "attrspat"); for (ATermIterator i(formals); i; ++i) { Expr name; ATerm dummy; if (!matchFormal(*i, name, dummy)) abort(); doc.writeEmptyElement("attr", singletonAttrs("name", aterm2String(name))); } + if (ellipsis == eTrue) doc.writeEmptyElement("ellipsis"); } else if (matchAtPat(pat, pat1, pat2)) { XMLOpenElement _(doc, "at"); diff --git a/src/libexpr/lexer.l b/src/libexpr/lexer.l index b7c1d19f8a5c..81aec99e15c8 100644 --- a/src/libexpr/lexer.l +++ b/src/libexpr/lexer.l @@ -95,6 +95,7 @@ let { return LET; } in { return IN; } rec { return REC; } inherit { return INHERIT; } +\.\.\. { return ELLIPSIS; } \=\= { return EQ; } \!\= { return NEQ; } diff --git a/src/libexpr/nixexpr-ast.def b/src/libexpr/nixexpr-ast.def index 670db1976fa3..ab749b3dbe84 100644 --- a/src/libexpr/nixexpr-ast.def +++ b/src/libexpr/nixexpr-ast.def @@ -66,7 +66,7 @@ PrimOp | int ATermBlob ATermList | Expr | Attrs | ATermList | Expr | Closed | Expr | Expr | Rec | ATermList ATermList | Expr | -Bool | ATerm | Expr | +Bool | ATermBool | Expr | Null | | Expr | Bind | string Expr Pos | ATerm | @@ -76,7 +76,7 @@ Inherit | Expr ATermList Pos | ATerm | Scope | | Expr | VarPat | string | Pattern | -AttrsPat | ATermList | Pattern | +AttrsPat | ATermList ATermBool | Pattern | # bool = `...' AtPat | Pattern Pattern | Pattern | Formal | string DefaultValue | ATerm | @@ -84,8 +84,8 @@ Formal | string DefaultValue | ATerm | DefaultValue | Expr | DefaultValue | NoDefaultValue | | DefaultValue | -True | | ATerm | -False | | ATerm | +True | | ATermBool | +False | | ATermBool | PrimOpDef | int ATermBlob | ATerm | diff --git a/src/libexpr/nixexpr.cc b/src/libexpr/nixexpr.cc index b2d775abbcc2..d96b5be97fb9 100644 --- a/src/libexpr/nixexpr.cc +++ b/src/libexpr/nixexpr.cc @@ -114,12 +114,13 @@ static void varsBoundByPattern(ATermMap & map, Pattern pat) { ATerm name; ATermList formals; - Pattern pat1, pat2; + Pattern pat1, pat2; + ATermBool ellipsis; /* Use makeRemoved() so that it can be used directly in substitute(). */ if (matchVarPat(pat, name)) map.set(name, makeRemoved()); - else if (matchAttrsPat(pat, formals)) { + else if (matchAttrsPat(pat, formals, ellipsis)) { for (ATermIterator i(formals); i; ++i) { ATerm d1; if (!matchFormal(*i, name, d1)) abort(); diff --git a/src/libexpr/nixexpr.hh b/src/libexpr/nixexpr.hh index 320d1dc977c5..43ac19f92a24 100644 --- a/src/libexpr/nixexpr.hh +++ b/src/libexpr/nixexpr.hh @@ -24,6 +24,7 @@ typedef ATerm Expr; typedef ATerm DefaultValue; typedef ATerm Pos; typedef ATerm Pattern; +typedef ATerm ATermBool; /* A STL vector of ATerms. Should be used with great care since it's diff --git a/src/libexpr/parser.y b/src/libexpr/parser.y index c48aa34aaf48..b7624df7e8aa 100644 --- a/src/libexpr/parser.y +++ b/src/libexpr/parser.y @@ -208,16 +208,22 @@ static void freeAndUnprotect(void * p) %union { ATerm t; ATermList ts; + struct { + ATermList formals; + bool ellipsis; + } formals; } %type start expr expr_function expr_if expr_op %type expr_app expr_select expr_simple bind inheritsrc formal %type pattern pattern2 -%type binds ids expr_list formals string_parts ind_string_parts +%type binds ids expr_list string_parts ind_string_parts +%type formals %token ID INT STR IND_STR PATH URI %token IF THEN ELSE ASSERT WITH LET IN REC INHERIT EQ NEQ AND OR IMPL %token DOLLAR_CURLY /* == ${ */ %token IND_STRING_OPEN IND_STRING_CLOSE +%token ELLIPSIS %nonassoc IMPL %left OR @@ -326,7 +332,7 @@ pattern pattern2 : ID { $$ = makeVarPat($1); } - | '{' formals '}' { $$ = makeAttrsPat($2); } + | '{' formals '}' { $$ = makeAttrsPat($2.formals, $2.ellipsis ? eTrue : eFalse); } ; binds @@ -357,9 +363,14 @@ expr_list ; formals - : formal ',' formals { $$ = ATinsert($3, $1); } /* idem - right recursive */ - | formal { $$ = ATinsert(ATempty, $1); } - | { $$ = ATempty; } + : formal ',' formals /* idem - right recursive */ + { $$.formals = ATinsert($3.formals, $1); $$.ellipsis = $3.ellipsis; } + | formal + { $$.formals = ATinsert(ATempty, $1); $$.ellipsis = false; } + | + { $$.formals = ATempty; $$.ellipsis = false; } + | ELLIPSIS + { $$.formals = ATempty; $$.ellipsis = true; } ; formal @@ -401,13 +412,14 @@ static void checkPatternVars(ATerm pos, ATermMap & map, Pattern pat) ATerm name; ATermList formals; Pattern pat1, pat2; + ATermBool ellipsis; if (matchVarPat(pat, name)) { if (map.get(name)) throw EvalError(format("duplicate formal function argument `%1%' at %2%") % aterm2String(name) % showPos(pos)); map.set(name, name); } - else if (matchAttrsPat(pat, formals)) { + else if (matchAttrsPat(pat, formals, ellipsis)) { for (ATermIterator i(formals); i; ++i) { ATerm d1; if (!matchFormal(*i, name, d1)) abort(); -- cgit 1.4.1