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

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that it can be used by multiple programs.
This commit is contained in:
Eelco Dolstra 2003-11-19 11:35:41 +00:00
parent 2be8b5917a
commit ac68840e79
15 changed files with 3 additions and 2 deletions
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164
src/nix-instantiate/parser.cc
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@ -1,164 +0,0 @@
#include <sstream>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
extern "C" {
#include <sglr.h>
#include <asfix2.h>
}
#include "aterm.hh"
#include "parser.hh"
#include "shared.hh"
#include "parse-table.h"
/* Cleanup cleans up an imploded parse tree into an actual abstract
syntax tree that we can evaluate. It removes quotes around
strings, converts integer literals into actual integers, and
absolutises paths relative to the directory containing the input
file. */
struct Cleanup : TermFun
{
string basePath;
virtual ATerm operator () (ATerm e)
{
ATMatcher m;
string s;
if (atMatch(m, e) >> "Str" >> s) {
return ATmake("Str(<str>)",
string(s, 1, s.size() - 2).c_str());
}
if (atMatch(m, e) >> "Path" >> s) {
if (s[0] != '/')
s = basePath + "/" + s;
return ATmake("Path(<str>)", canonPath(s).c_str());
}
if (atMatch(m, e) >> "Int" >> s) {
istringstream s2(s);
int n;
s2 >> n;
return ATmake("Int(<int>)", n);
}
if (atMatch(m, e) >> "Bool" >> "true")
return ATmake("Bool(True)");
if (atMatch(m, e) >> "Bool" >> "false")
return ATmake("Bool(False)");
if (atMatch(m, e) >> "ExprNil")
return (ATerm) ATempty;
ATerm e1;
ATermList e2;
if (atMatch(m, e) >> "ExprCons" >> e1 >> e2)
return (ATerm) ATinsert(e2, e1);
return e;
}
};
Expr parseExprFromFile(Path path)
{
#if 0
/* Perhaps this is already an imploded parse tree? */
Expr e = ATreadFromNamedFile(path.c_str());
if (e) return e;
#endif
/* If `path' refers to a directory, append `/default.nix'. */
struct stat st;
if (stat(path.c_str(), &st))
throw SysError(format("getting status of `%1%'") % path);
if (S_ISDIR(st.st_mode))
path = canonPath(path + "/default.nix");
/* Initialise the SDF libraries. */
static bool initialised = false;
static ATerm parseTable = 0;
static language lang = 0;
if (!initialised) {
PT_initMEPTApi();
PT_initAsFix2Api();
SGinitParser(ATfalse);
ATprotect(&parseTable);
parseTable = ATreadFromBinaryString(
(char *) nixParseTable, sizeof nixParseTable);
if (!parseTable)
throw Error(format("cannot construct parse table term"));
ATprotect(&lang);
lang = ATmake("Nix");
if (!SGopenLanguageFromTerm(
(char *) programId.c_str(), lang, parseTable))
throw Error(format("cannot open language"));
SG_STARTSYMBOL_ON();
SG_OUTPUT_ON();
SG_ASFIX2ME_ON();
SG_AMBIGUITY_ERROR_ON();
SG_FILTER_OFF();
initialised = true;
}
/* Read the input file. We can't use SGparseFile() because it's
broken, so we read the input ourselves and call
SGparseString(). */
AutoCloseFD fd = open(path.c_str(), O_RDONLY);
if (fd == -1) throw SysError(format("opening `%1%'") % path);
if (fstat(fd, &st) == -1)
throw SysError(format("statting `%1%'") % path);
char text[st.st_size + 1];
readFull(fd, (unsigned char *) text, st.st_size);
text[st.st_size] = 0;
/* Parse it. */
ATerm result = SGparseString(lang, "Expr", text);
if (!result)
throw SysError(format("parse failed in `%1%'") % path);
if (SGisParseError(result))
throw Error(format("parse error in `%1%': %2%")
% path % result);
/* Implode it. */
PT_ParseTree tree = PT_makeParseTreeFromTerm(result);
if (!tree)
throw Error(format("cannot create parse tree"));
ATerm imploded = PT_implodeParseTree(tree,
ATtrue,
ATtrue,
ATtrue,
ATtrue,
ATtrue,
ATtrue,
ATfalse,
ATtrue,
ATtrue,
ATtrue,
ATfalse);
if (!imploded)
throw Error(format("cannot implode parse tree"));
printMsg(lvlVomit, format("imploded parse tree of `%1%': %2%")
% path % imploded);
/* Finally, clean it up. */
Cleanup cleanup;
cleanup.basePath = dirOf(path);
return bottomupRewrite(cleanup, imploded);
}