lix-releng-staging/nix-repl.cc
Eelco Dolstra 287c88ca59 Support adding variables to the scope
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 ]
2013-09-02 17:53:58 +02:00

135 lines
2.4 KiB
C++
Raw Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

#include <iostream>
#include <cstdlib>
#include <readline/readline.h>
#include <readline/history.h>
#include "shared.hh"
#include "eval.hh"
#include "eval-inline.hh"
#include "store-api.hh"
using namespace std;
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";
}
bool getLine(string & line)
{
char * s = readline("nix-repl> ");
if (!s) return false;
line = chomp(string(s));
free(s);
if (line != "") add_history(line.c_str());
return true;
}
NixRepl::NixRepl()
: staticEnv(false, &state.staticBaseEnv)
{
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 {
processLine(line);
} catch (Error & e) {
printMsg(lvlError, e.msg());
}
std::cout << std::endl;
}
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();
}