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Support adding variables to the scope

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The command ":a <expr>" evaluates <expr> and adds the attributes in
the resulting attribute set to the interpreter scope.  For instance:

nix-repl> :a import <nixpkgs> {}

nix-repl> lib.range 0 10
[ 0 1 2 3 4 5 6 7 8 9 10 ]
This commit is contained in:
Eelco Dolstra 2013-09-02 17:53:58 +02:00
parent e90569905e
commit 287c88ca59
1 changed files with 86 additions and 9 deletions
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93
nix-repl.cc
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@ -6,6 +6,8 @@
#include "shared.hh"
#include "eval.hh"
#include "eval-inline.hh"
#include "store-api.hh"
using namespace std;
using namespace nix;
@ -14,6 +16,23 @@ using namespace nix;
string programId = "nix-repl";
struct NixRepl
{
string curDir;
EvalState state;
StaticEnv staticEnv;
Env * env;
int displ;
NixRepl();
void mainLoop();
void processLine(string line);
void addVar(const Symbol & name, Value * v);
Expr * parseString(string s);
};
void printHelp()
{
std::cout << "Usage: nix-repl\n";
@ -31,21 +50,33 @@ bool getLine(string & line)
}
void run(nix::Strings args)
NixRepl::NixRepl()
: staticEnv(false, &state.staticBaseEnv)
{
EvalState state;
Path curDir = absPath(".");
curDir = absPath(".");
env = &state.allocEnv(32768);
env->up = &state.baseEnv;
displ = 0;
store = openStore();
}
void NixRepl::mainLoop()
{
std::cerr << "Welcome to Nix version " << NIX_VERSION << ". Type :? for help." << std::endl << std::endl;
while (true) {
string line;
if (!getLine(line)) break;
/* Remove preceeding whitespace. */
size_t n = line.find_first_not_of(" \n\r\t");
if (n != string::npos) line = string(line, n);
try {
Expr * e = state.parseExprFromString(line, curDir);
Value v;
state.eval(e, v);
state.strictForceValue(v);
std::cout << v << std::endl;
processLine(line);
} catch (Error & e) {
printMsg(lvlError, e.msg());
}
@ -55,3 +86,49 @@ void run(nix::Strings args)
std::cout << std::endl;
}
void NixRepl::processLine(string line)
{
if (string(line, 0, 2) == ":a") {
Expr * e = parseString(string(line, 2));
Value v;
e->eval(state, *env, v);
state.forceAttrs(v);
foreach (Bindings::iterator, i, *v.attrs)
addVar(i->name, i->value);
}
else if (string(line, 0, 1) == ":") {
throw Error(format("unknown command ‘%1%’") % string(line, 0, 2));
}
else {
Expr * e = parseString(line);
Value v;
e->eval(state, *env, v);
state.strictForceValue(v);
std::cout << v << std::endl;
}
}
void NixRepl::addVar(const Symbol & name, Value * v)
{
staticEnv.vars[name] = displ;
env->values[displ++] = v;
}
Expr * NixRepl::parseString(string s)
{
Expr * e = state.parseExprFromString(s, curDir, staticEnv);
return e;
}
void run(nix::Strings args)
{
NixRepl repl;
repl.mainLoop();
}