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env.js
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env.js
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// Node vs browser behavior
var env = {};
if (typeof module === 'undefined') {
var exports = env;
}
// Env implementation
function Env(outer, binds, exprs) {
this.data = {};
this.outer = outer || null;
if (binds && exprs) {
// Returns a new Env with symbols in binds bound to
// corresponding values in exprs
// TODO: check types of binds and exprs and compare lengths
for (var i=0; i<binds.length;i++) {
if (binds[i].value === "&") {
// variable length arguments
this.data[binds[i+1].value] = Array.prototype.slice.call(exprs, i);
break;
} else {
this.data[binds[i].value] = exprs[i];
}
}
}
return this;
}
Env.prototype.find = function (key) {
if (!key.constructor || key.constructor.name !== 'Symbol') {
throw new Error("env.find key must be a symbol")
}
if (key.value in this.data) { return this; }
else if (this.outer) { return this.outer.find(key); }
else { return null; }
};
Env.prototype.set = function(key, value) {
if (!key.constructor || key.constructor.name !== 'Symbol') {
throw new Error("env.set key must be a symbol")
}
this.data[key.value] = value;
return value;
};
Env.prototype.get = function(key) {
if (!key.constructor || key.constructor.name !== 'Symbol') {
throw new Error("env.get key must be a symbol")
}
var env = this.find(key);
if (!env) { throw new Error("'" + key.value + "' not found"); }
return env.data[key.value];
};
exports.Env = env.Env = Env;