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-rw-r--r--src/eval.cc276
-rw-r--r--src/eval.hh79
-rw-r--r--src/globals.cc2
-rw-r--r--src/globals.hh21
-rw-r--r--src/hash.cc4
-rw-r--r--src/hash.hh4
-rw-r--r--src/test.cc36
-rw-r--r--src/util.cc4
-rw-r--r--src/util.hh7
-rw-r--r--src/values.cc50
-rw-r--r--src/values.hh20
11 files changed, 136 insertions, 367 deletions
diff --git a/src/eval.cc b/src/eval.cc
index 831464c18..4f59bcc21 100644
--- a/src/eval.cc
+++ b/src/eval.cc
@@ -30,6 +30,7 @@ bool pathExists(string path)
}
+#if 0
/* Compute a derived value by running a program. */
static Hash computeDerived(Hash sourceHash, string targetName,
string platform, Hash prog, Environment env)
@@ -175,6 +176,7 @@ static Hash computeDerived(Hash sourceHash, string targetName,
return targetHash;
}
+#endif
/* Throw an exception if the given platform string is not supported by
@@ -182,52 +184,30 @@ static Hash computeDerived(Hash sourceHash, string targetName,
static void checkPlatform(string platform)
{
if (platform != thisSystem)
- throw Error("a `" + platform +
- "' is required, but I am a `" + thisSystem + "'");
+ throw Error(format("a `%1%' is required, but I am a `%2%'")
+ % platform % thisSystem);
}
-string printExpr(Expr e)
+string printTerm(ATerm t)
{
- char * s = ATwriteToString(e);
+ char * s = ATwriteToString(t);
return s;
}
/* Throw an exception with an error message containing the given
aterm. */
-static Error badTerm(const string & msg, Expr e)
-{
- return Error(msg + ", in `" + printExpr(e) + "'");
-}
-
-
-Hash hashExpr(Expr e)
+static Error badTerm(const format & f, ATerm t)
{
- return hashString(printExpr(e));
+ return Error(format("%1%, in `%2%'") % f.str() % printTerm(t));
}
-/* Evaluate an expression; the result must be a string. */
-static string evalString(Expr e)
-{
- e = whNormalise(e);
- char * s;
- if (ATmatch(e, "Str(<str>)", &s)) return s;
- else throw badTerm("string value expected", e);
-}
-
-
-#if 0
-/* Evaluate an expression; the result must be a value reference. */
-static Hash evalHash(Expr e)
+Hash hashTerm(ATerm t)
{
- e = evalValue(e);
- char * s;
- if (ATmatch(e, "Hash(<str>)", &s)) return parseHash(s);
- else throw badTerm("value reference expected", e);
+ return hashString(printTerm(t));
}
-#endif
#if 0
@@ -262,225 +242,63 @@ void evalArgs(ATermList args, ATermList & argsNF, Environment & env)
#endif
-Expr substExpr(string x, Expr rep, Expr e)
-{
- char * s;
- Expr e2;
-
- if (ATmatch(e, "Var(<str>)", &s))
- if (x == s)
- return rep;
- else
- return e;
-
- if (ATmatch(e, "Lam(<str>, <term>)", &s, &e2))
- if (x == s)
- return e;
- /* !!! unfair substitutions */
-
- /* Generically substitute in subterms. */
-
- if (ATgetType(e) == AT_APPL) {
- AFun fun = ATgetAFun(e);
- int arity = ATgetArity(fun);
- ATermList args = ATempty;
-
- for (int i = arity - 1; i >= 0; i--)
- args = ATinsert(args, substExpr(x, rep, ATgetArgument(e, i)));
-
- return (ATerm) ATmakeApplList(fun, args);
- }
-
- if (ATgetType(e) == AT_LIST) {
- ATermList in = (ATermList) e;
- ATermList out = ATempty;
-
- while (!ATisEmpty(in)) {
- out = ATinsert(out, substExpr(x, rep, ATgetFirst(in)));
- in = ATgetNext(in);
- }
-
- return (ATerm) ATreverse(out);
- }
-
- throw badTerm("do not know how to substitute", e);
-}
-
-
-#if 0
-Expr evalValue(Expr e)
-{
- char * s;
- Expr eBuildPlatform, eProg, e2, e3, e4;
- ATermList args;
-
- /* Value references. */
- if (ATmatch(e, "Hash(<str>)", &s)) {
- parseHash(s); /* i.e., throw exception if not valid */
- return e;
- }
-
- /* External expression. */
- if (ATmatch(e, "Deref(<term>)", &e2)) {
- string fn = queryValuePath(evalHash(e2));
- ATerm e3 = ATreadFromNamedFile(fn.c_str());
- if (!e3) throw Error("reading aterm from " + fn);
- return evalValue(e3);
- }
-
- /* Execution primitive. */
-
- if (ATmatch(e, "Exec(<term>, <term>, [<list>])",
- &eBuildPlatform, &eProg, &args))
- {
- string buildPlatform = evalString(eBuildPlatform);
-
- checkPlatform(buildPlatform);
-
- Hash prog = evalHash(eProg);
-
- Environment env;
- ATermList argsNF;
- evalArgs(args, argsNF, env);
-
- Hash sourceHash = hashExpr(
- ATmake("Exec(Str(<str>), Hash(<str>), <term>)",
- buildPlatform.c_str(), ((string) prog).c_str(), argsNF));
-
- /* Do we know a normal form for sourceHash? */
- Hash targetHash;
- string targetHashS;
- if (queryDB(nixDB, dbNFs, sourceHash, targetHashS)) {
- /* Yes. */
- targetHash = parseHash(targetHashS);
- debug("already built: " + (string) sourceHash
- + " -> " + (string) targetHash);
- } else {
- /* No, so we compute one. */
- targetHash = computeDerived(sourceHash,
- (string) sourceHash + "-nf", buildPlatform, prog, env);
- }
-
- return ATmake("Hash(<str>)", ((string) targetHash).c_str());
- }
-
- /* Barf. */
- throw badTerm("invalid expression", e);
-}
-#endif
-
-
-Expr whNormalise(Expr e)
-{
- char * s;
- Expr e2, e3, e4, e5;
-
- /* Normal forms. */
- if (ATmatch(e, "Str(<str>)", &s) ||
- ATmatch(e, "Bool(True)") ||
- ATmatch(e, "Bool(False)") ||
- ATmatch(e, "Lam(<str>, <term>)", &s, &e2) ||
- ATmatch(e, "File(<str>, <term>, <term>)", &s, &e2, &e3) ||
- ATmatch(e, "Derive(<term>, <term>, <term>, <term>)", &e2, &e3, &e4, &e5))
- return e;
-
- /* Application. */
- if (ATmatch(e, "App(<term>, <term>)", &e2, &e3)) {
- e2 = whNormalise(e2);
- if (!ATmatch(e2, "Lam(<str>, <term>)", &s, &e4))
- throw badTerm("expecting lambda", e2);
- return whNormalise(substExpr(s, e3, e4));
- }
-
- throw badTerm("invalid expression", e);
-}
-
-
-Expr dNormalise(Expr e)
+struct RStatus
{
- e = whNormalise(e);
- /* !!! todo */
- return e;
-}
+ /* !!! the comparator of this hash should match the semantics of
+ the file system */
+// map<string, Hash> paths;
+};
-Expr fNormalise(Expr e)
+static void realise(RStatus & status, FState fs)
{
- e = dNormalise(e);
-
char * s;
- Expr e2, e3;
+ Content content;
+ ATermList refs;
+
+ if (ATmatch(fs, "File(<str>, <term>, [<list>])", &s, &content, &refs)) {
+ string path(s);
- if (ATmatch(e, "File(<str>, <term>, [<list>])", &s, &e2, &e3)) {
+ if (path[0] != '/') throw Error("absolute path expected: " + path);
- ATermList refs = (ATermList) e3, refs2 = ATempty;
+ /* Realise referenced paths. */
while (!ATisEmpty(refs)) {
- ATerm ref = ATgetFirst(refs);
- refs2 = ATinsert(refs2, fNormalise(ref));
+ realise(status, ATgetFirst(refs));
refs = ATgetNext(refs);
}
- refs2 = ATreverse(refs2);
-
- return ATmake("File(<str>, <term>, <term>)", s, e2, refs2);
-
- }
-
- else return e;
-}
-
-
-void writeContent(string path, Content content)
-{
- char * s;
- if (ATmatch(content, "Regular(<str>)", &s)) {
+ if (!ATmatch(content, "Hash(<str>)", &s))
+ throw badTerm("hash expected", content);
+ Hash hash = parseHash(s);
- int fd; /* !!! close on exception */
- fd = open(path.c_str(), O_CREAT | O_EXCL | O_WRONLY, 0666);
- if (fd == -1)
- throw SysError("creating file " + path);
+ /* Perhaps the path already exists and has the right hash? */
+ if (pathExists(path)) {
+ if (hash == hashPath(path)) {
+ debug(format("path %1% already has hash %2%")
+ % path % (string) hash);
+ return;
+ }
- int len = strlen(s);
- if (write(fd, s, len) != len)
- throw SysError("writing file " + path);
+ throw Error(format("path %1% exists, but does not have hash %2%")
+ % path % (string) hash);
+ }
- close(fd);
+ /* Do we know a path with that hash? If so, copy it. */
+ string path2 = queryFromStore(hash);
+ copyFile(path2, path);
}
-
- else throw badTerm("ill-formed content", content);
-}
-
-
-struct RStatus
-{
- /* !!! the comparator of this hash should match the semantics of
- the file system */
- map<string, Hash> paths;
-};
-
-static void realise2(RStatus & status, Expr e)
-{
- char * s;
- Content content;
- ATermList refs;
-
- if (!ATmatch(e, "File(<str>, <term>, [<list>])", &s, &content, &refs))
- throw badTerm("not f-normalised", e);
-
- string path(s);
-
- while (!ATisEmpty(refs)) {
- realise2(status, ATgetFirst(refs));
- refs = ATgetNext(refs);
+ else if (ATmatch(fs, "Derive()")) {
+
+
}
-
- writeContent(path, content);
+
+ else throw badTerm("bad file system state expression", fs);
}
-void realise(Expr e)
+void realiseFState(FState fs)
{
RStatus status;
- realise2(status, e);
+ realise(status, fs);
}
diff --git a/src/eval.hh b/src/eval.hh
index 807f98f85..f90d5ba02 100644
--- a/src/eval.hh
+++ b/src/eval.hh
@@ -10,14 +10,12 @@ extern "C" {
using namespace std;
-/* \section{Abstract syntax of Nix expressions}
+/* \section{Abstract syntax of Nix file system state expressions}
- An expression describes a (partial) state of the file system in a
- referentially transparent way. The operational effect of
- evaluating an expression is that the state described by the
- expression is realised.
+ A Nix file system state expression, or FState, describes a
+ (partial) state of the file system.
- File : Path * Content * [Expr] -> Expr
+ File : Path * Content * [FState] -> FState
File(path, content, refs) specifies a file object (its full path
and contents), along with all file objects referenced by it (that
@@ -25,7 +23,7 @@ using namespace std;
self-referential. This prevents us from having to deal with
cycles.
- Derive : String * Path * [Expr] * [Expr] * [Expr] -> Expr
+ Derive : String * Path * [FState] * [Path] * [(String, String)] -> [FState]
Derive(platform, builder, ins, outs, env) specifies the creation of
new file objects (in paths declared by `outs') by the execution of
@@ -33,14 +31,6 @@ using namespace std;
place in a file system state given by `ins'. `env' specifies a
mapping of strings to strings.
- Str : String -> Expr
-
- A string constant.
-
- Tup : Expr * Expr -> Expr
-
- Tuples of expressions.
-
[ !!! NOT IMPLEMENTED
Regular : String -> Content
Directory : [(String, Content)] -> Content
@@ -49,7 +39,11 @@ using namespace std;
CHash : Hash -> Content
File content, given either in situ, or through an external reference
- to the file system or url-space decorated with a hash to preserve purity.
+ to the file system or url-space decorated with a hash to preserve
+ purity.
+
+ A FState expression is in {\em $f$-normal form} if all Derive nodes
+ have been reduced to File nodes.
DISCUSSION: the idea is that a Regular/Directory is interchangeable
with its CHash. This would appear to break referential
@@ -60,63 +54,20 @@ using namespace std;
CHash, we should also export the file object referenced by that
CHash.
-
- \section{Reduction rules}
-
- ...
-
-
- \section{Normals forms}
-
- An expression is in {\em weak head normal form} if it is a lambda,
- a string or boolean value, or a File or Derive value.
-
- An expression is in {\em $d$-normal form} if it matches the
- signature FExpr:
-
- File : String * Content * [DExpr] -> DExpr
- Derive : String * Path * [Tup] * [Tup2] -> DExpr
-
- Tup : Str * DExpr -> Tup
- Tup : Str * Str -> Tup
-
- Tup : Str * Str -> Tup2
-
- Str : String -> Str
-
- These are Nix expressions in which the file system result of Derive
- expressions has not yet been computed. This is useful for, e.g.,
- querying dependencies.
-
- An expression is in {\em $f$-normal form} if it matches the
- signature FExpr:
-
- File : String * Content * [FExpr] -> FExpr
-
- These are completely evaluated Nix expressions.
-
*/
-typedef ATerm Expr;
+typedef ATerm FState;
typedef ATerm Content;
-/* Expression normalisation. */
-Expr whNormalise(Expr e);
-Expr dNormalise(Expr e);
-Expr fNormalise(Expr e);
-
/* Realise a $f$-normalised expression in the file system. */
-void realise(Expr e);
+void realiseFState(FState fs);
/* Return a canonical textual representation of an expression. */
-string printExpr(Expr e);
-
-/* Perform variable substitution. */
-Expr substExpr(string x, Expr rep, Expr e);
+string printTerm(ATerm t);
-/* Hash an expression. */
-Hash hashExpr(Expr e);
+/* Hash an aterm. */
+Hash hashTerm(ATerm t);
#endif /* !__EVAL_H */
diff --git a/src/globals.cc b/src/globals.cc
index 14fb431d8..640e960b1 100644
--- a/src/globals.cc
+++ b/src/globals.cc
@@ -6,7 +6,7 @@ string dbRefs = "refs";
string dbNFs = "nfs";
string dbNetSources = "netsources";
-string nixValues = "/UNINIT";
+string nixStore = "/UNINIT";
string nixLogDir = "/UNINIT";
string nixDB = "/UNINIT";
diff --git a/src/globals.hh b/src/globals.hh
index b81a78714..3cb231ee2 100644
--- a/src/globals.hh
+++ b/src/globals.hh
@@ -8,15 +8,10 @@ using namespace std;
/* Database names. */
-/* dbRefs :: Hash -> FileName
-
- Maintains a mapping from hashes to filenames within the NixValues
- directory. This mapping is for performance only; it can be
- reconstructed unambiguously. The reason is that names in this
- directory are not printed hashes but also might carry some
- descriptive element (e.g., "aterm-2.0-ae749a..."). Without this
- mapping, looking up a value would take O(n) time because we would
- need to read the entire directory. */
+/* dbRefs :: Hash -> Path
+
+ Maintains a mapping from hashes to paths. This is what we use to
+ resolve CHash(hash) content descriptors. */
extern string dbRefs;
/* dbNFs :: Hash -> Hash
@@ -45,11 +40,11 @@ extern string dbNetSources;
/* Path names. */
-/* nixValues is the directory where all Nix values (both files and
- directories, and both normal and non-normal forms) live. */
-extern string nixValues;
+/* nixStore is the directory where we generally store atomic and
+ derived files. */
+extern string nixStore;
-/* nixLogDir is the directory where we log evaluations. */
+/* nixLogDir is the directory where we log various operations. */
extern string nixLogDir;
/* nixDB is the file name of the Berkeley DB database where we
diff --git a/src/hash.cc b/src/hash.cc
index 765b7ba04..72dcd790c 100644
--- a/src/hash.cc
+++ b/src/hash.cc
@@ -14,7 +14,7 @@ Hash::Hash()
}
-bool Hash::operator == (Hash & h2)
+bool Hash::operator == (Hash h2)
{
for (unsigned int i = 0; i < hashSize; i++)
if (hash[i] != h2.hash[i]) return false;
@@ -22,7 +22,7 @@ bool Hash::operator == (Hash & h2)
}
-bool Hash::operator != (Hash & h2)
+bool Hash::operator != (Hash h2)
{
return !(*this == h2);
}
diff --git a/src/hash.hh b/src/hash.hh
index cbc195c1f..509a27912 100644
--- a/src/hash.hh
+++ b/src/hash.hh
@@ -17,10 +17,10 @@ struct Hash
Hash();
/* Check whether two hash are equal. */
- bool operator == (Hash & h2);
+ bool operator == (Hash h2);
/* Check whether two hash are not equal. */
- bool operator != (Hash & h2);
+ bool operator != (Hash h2);
/* Convert a hash code into a hexadecimal representation. */
operator string() const;
diff --git a/src/test.cc b/src/test.cc
index d912eaa6a..aafae8ee3 100644
--- a/src/test.cc
+++ b/src/test.cc
@@ -11,20 +11,16 @@
#include "globals.hh"
-typedef Expr (* Normaliser) (Expr);
-
-
-void eval(Normaliser n, Expr e)
+void realise(FState fs)
{
- e = n(e);
- cout << (string) hashExpr(e) << ": " << printExpr(e) << endl;
+ realiseFState(fs);
}
-void evalFail(Normaliser n, Expr e)
+void realiseFail(FState fs)
{
try {
- e = n(e);
+ realiseFState(fs);
abort();
} catch (Error e) {
cout << "error (expected): " << e.what() << endl;
@@ -96,7 +92,7 @@ void runTests()
string testDir = absPath("scratch");
cout << testDir << endl;
- nixValues = testDir;
+ nixStore = testDir;
nixLogDir = testDir;
nixDB = testDir + "/db";
@@ -104,6 +100,7 @@ void runTests()
/* Expression evaluation. */
+#if 0
eval(whNormalise,
ATmake("Str(\"Hello World\")"));
eval(whNormalise,
@@ -138,10 +135,27 @@ void runTests()
eval(fNormalise, e2);
realise(e2);
+#endif
-#if 0
- Hash builder1 = addValue("./test-builder-1.sh");
+ Hash builder1h;
+ string builder1fn;
+ addToStore("./test-builder-1.sh", builder1fn, builder1h);
+
+ FState fs1 = ATmake(
+ "File(<str>, Hash(<str>), [])",
+ builder1fn.c_str(),
+ ((string) builder1h).c_str());
+ realiseFState(fs1);
+ realiseFState(fs1);
+ FState fs2 = ATmake(
+ "File(<str>, Hash(<str>), [])",
+ (builder1fn + "_bla").c_str(),
+ ((string) builder1h).c_str());
+ realiseFState(fs2);
+ realiseFState(fs2);
+
+#if 0
Expr e1 = ATmake("Exec(Str(<str>), Hash(<str>), [])",
thisSystem.c_str(), ((string) builder1).c_str());
diff --git a/src/util.cc b/src/util.cc
index 4dada48ba..c6a0c1199 100644
--- a/src/util.cc
+++ b/src/util.cc
@@ -78,7 +78,7 @@ void deletePath(string path)
}
-void debug(string s)
+void debug(const format & f)
{
- cerr << "debug: " << s << endl;
+ cerr << format("debug: %1%\n") % f.str();
}
diff --git a/src/util.hh b/src/util.hh
index 7d5f00a2e..3efac928b 100644
--- a/src/util.hh
+++ b/src/util.hh
@@ -7,7 +7,10 @@
#include <unistd.h>
+#include <boost/format.hpp>
+
using namespace std;
+using namespace boost;
class Error : public exception
@@ -16,7 +19,7 @@ protected:
string err;
public:
Error() { }
- Error(string _err) { err = _err; }
+ Error(format f) { err = f.str(); }
~Error() throw () { }
const char * what() const throw () { return err.c_str(); }
};
@@ -59,7 +62,7 @@ string baseNameOf(string path);
void deletePath(string path);
-void debug(string s);
+void debug(const format & f);
#endif /* !__UTIL_H */
diff --git a/src/values.cc b/src/values.cc
index c8a3b58cb..e23624ce5 100644
--- a/src/values.cc
+++ b/src/values.cc
@@ -34,7 +34,7 @@ struct CopySource : RestoreSource
};
-static void copyFile(string src, string dst)
+void copyFile(string src, string dst)
{
/* Unfortunately C++ doesn't support coprocedures, so we have no
nice way to chain CopySink and CopySource together. Instead we
@@ -83,33 +83,25 @@ static void copyFile(string src, string dst)
}
-static string absValuePath(string s)
+void addToStore(string srcPath, string & dstPath, Hash & hash)
{
- return nixValues + "/" + s;
-}
-
-
-Hash addValue(string path)
-{
- path = absPath(path);
+ srcPath = absPath(srcPath);
- Hash hash = hashPath(path);
+ hash = hashPath(srcPath);
- string name;
- if (queryDB(nixDB, dbRefs, hash, name)) {
+ string path;
+ if (queryDB(nixDB, dbRefs, hash, path)) {
debug((string) hash + " already known");
- return hash;
+ dstPath = path;
+ return;
}
- string baseName = baseNameOf(path);
-
- string targetName = (string) hash + "-" + baseName;
+ string baseName = baseNameOf(srcPath);
+ dstPath = nixStore + "/" + (string) hash + "-" + baseName;
- copyFile(path, absValuePath(targetName));
+ copyFile(srcPath, dstPath);
- setDB(nixDB, dbRefs, hash, targetName);
-
- return hash;
+ setDB(nixDB, dbRefs, hash, dstPath);
}
@@ -135,28 +127,28 @@ string fetchURL(string url)
#endif
-void deleteValue(Hash hash)
+void deleteFromStore(Hash hash)
{
- string name;
- if (queryDB(nixDB, dbRefs, hash, name)) {
- string fn = absValuePath(name);
+ string fn;
+ if (queryDB(nixDB, dbRefs, hash, fn)) {
+ string prefix = nixStore + "/";
+ if (string(fn, prefix.size()) != prefix)
+ throw Error("path " + fn + " is not in the store");
deletePath(fn);
delDB(nixDB, dbRefs, hash);
}
}
-/* !!! bad name, "query" implies no side effect => getValuePath() */
-string queryValuePath(Hash hash)
+string queryFromStore(Hash hash)
{
bool checkedNet = false;
while (1) {
- string name, url;
+ string fn, url;
- if (queryDB(nixDB, dbRefs, hash, name)) {
- string fn = absValuePath(name);
+ if (queryDB(nixDB, dbRefs, hash, fn)) {
/* Verify that the file hasn't changed. !!! race !!! slow */
if (hashPath(fn) != hash)
diff --git a/src/values.hh b/src/values.hh
index d66ae770f..1bb00a9dd 100644
--- a/src/values.hh
+++ b/src/values.hh
@@ -8,21 +8,17 @@
using namespace std;
-/* Copy a value to the nixValues directory and register it in dbRefs.
- Return the hash code of the value. */
-Hash addValue(string pathName);
-
+void copyFile(string src, string dst);
-/* Delete a value from the nixValues directory. */
-void deleteValue(Hash hash);
+/* Copy a file to the nixStore directory and register it in dbRefs.
+ Return the hash code of the value. */
+void addToStore(string srcPath, string & dstPath, Hash & hash);
+/* Delete a value from the nixStore directory. */
+void deleteFromStore(Hash hash);
-/* Obtain the path of a value with the given hash. If a file with
- that hash is known to exist in the local file system (as indicated
- by the dbRefs database), we use that. Otherwise, we attempt to
- fetch it from the network (using dbNetSources). We verify that the
- file has the right hash. */
-string queryValuePath(Hash hash);
+/* !!! */
+string queryFromStore(Hash hash);
#endif /* !__VALUES_H */
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-24 01:10:24 +0000