Skip to content

Navigation Menu

Sign in
Appearance settings

Search code, repositories, users, issues, pull requests...

Provide feedback

We read every piece of feedback, and take your input very seriously.

Saved searches

Use saved searches to filter your results more quickly
Sign up
Appearance settings

Commit 6287eae

Browse files
Create a_programming_languague_completejavascript.com.js
1 parent c94beaa commit 6287eae

File tree

1 file changed

+263
-0
lines changed

1 file changed

+263
-0
lines changed
Lines changed: 263 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,263 @@
1+
function parseExpression(program) {
2+
program = skipSpace(program);
3+
var match, expr;
4+
if (match = /^"([^"]*)"/.exec(program))
5+
expr = {type: "value", value: match[1]};
6+
else if (match = /^\d+\b/.exec(program))
7+
expr = {type: "value", value: Number(match[0])};
8+
else if (match = /^[^\s(),"]+/.exec(program))
9+
expr = {type: "word", name: match[0]};
10+
else
11+
throw new SyntaxError("Unexpected syntax: " + program);
12+
13+
return parseApply(expr, program.slice(match[0].length));
14+
}
15+
/*
16+
function skipSpace(string) {
17+
var first = string.search(/\S/);
18+
if (first == -1) return "";
19+
return string.slice(first);
20+
}
21+
*/
22+
23+
// This is the old skipSpace. Modify it...
24+
function skipSpace(string) {
25+
while(true)
26+
{
27+
var first = string.search(/\S/);
28+
if (first == -1) return "";
29+
30+
string = string.slice(first);
31+
if(string[0] != '#') return string;
32+
33+
first = string.search(/\n/);
34+
string = string.slice(first);
35+
}
36+
}
37+
38+
function parseApply(expr, program) {
39+
program = skipSpace(program);
40+
if (program[0] != "(")
41+
return {expr: expr, rest: program};
42+
43+
program = skipSpace(program.slice(1));
44+
expr = {type: "apply", operator: expr, args: []};
45+
while (program[0] != ")") {
46+
var arg = parseExpression(program);
47+
expr.args.push(arg.expr);
48+
program = skipSpace(arg.rest);
49+
if (program[0] == ",")
50+
program = skipSpace(program.slice(1));
51+
else if (program[0] != ")")
52+
throw new SyntaxError("Expected ',' or ')'");
53+
}
54+
return parseApply(expr, program.slice(1));
55+
}
56+
57+
function parse(program) {
58+
var result = parseExpression(program);
59+
if (skipSpace(result.rest).length > 0)
60+
throw new SyntaxError("Unexpected text after program");
61+
return result.expr;
62+
}
63+
64+
//console.log(parse("+(a, 10, 11)"));
65+
// → {type: "apply",
66+
// operator: {type: "word", name: "+"},
67+
// args: [{type: "word", name: "a"},
68+
// {type: "value", value: 10}]}
69+
70+
function evaluate(expr, env) {
71+
switch(expr.type) {
72+
case "value":
73+
return expr.value;
74+
75+
case "word":
76+
if (expr.name in env)
77+
return env[expr.name];
78+
else
79+
throw new ReferenceError("Undefined variable: " +
80+
expr.name);
81+
case "apply":
82+
if (expr.operator.type == "word" &&
83+
expr.operator.name in specialForms)
84+
return specialForms[expr.operator.name](expr.args,
85+
env);
86+
var op = evaluate(expr.operator, env);
87+
if (typeof op != "function")
88+
throw new TypeError("Applying a non-function.");
89+
return op.apply(null, expr.args.map(function(arg) {
90+
return evaluate(arg, env);
91+
}));
92+
}
93+
}
94+
95+
var specialForms = Object.create(null);
96+
97+
specialForms["if"] = function(args, env) {
98+
if (args.length != 3)
99+
throw new SyntaxError("Bad number of args to if");
100+
101+
if (evaluate(args[0], env) !== false)
102+
return evaluate(args[1], env);
103+
else
104+
return evaluate(args[2], env);
105+
};
106+
107+
specialForms["while"] = function(args, env) {
108+
if (args.length != 2)
109+
throw new SyntaxError("Bad number of args to while");
110+
111+
while (evaluate(args[0], env) !== false)
112+
evaluate(args[1], env);
113+
114+
// Since undefined does not exist in Egg, we return false,
115+
// for lack of a meaningful result.
116+
return false;
117+
};
118+
119+
specialForms["do"] = function(args, env) {
120+
var value = false;
121+
args.forEach(function(arg) {
122+
value = evaluate(arg, env);
123+
});
124+
return value;
125+
};
126+
127+
specialForms["define"] = function(args, env) {
128+
if (args.length != 2 || args[0].type != "word")
129+
throw new SyntaxError("Bad use of define");
130+
var value = evaluate(args[1], env);
131+
env[args[0].name] = value;
132+
return value;
133+
};
134+
135+
specialForms["fun"] = function(args, env) {
136+
if (!args.length)
137+
throw new SyntaxError("Functions need a body");
138+
function name(expr) {
139+
if (expr.type != "word")
140+
throw new SyntaxError("Arg names must be words");
141+
return expr.name;
142+
}
143+
var argNames = args.slice(0, args.length - 1).map(name);
144+
var body = args[args.length - 1];
145+
146+
return function() {
147+
if (arguments.length != argNames.length)
148+
throw new TypeError("Wrong number of arguments");
149+
var localEnv = Object.create(env);
150+
for (var i = 0; i < arguments.length; i++)
151+
localEnv[argNames[i]] = arguments[i];
152+
return evaluate(body, localEnv);
153+
};
154+
};
155+
156+
specialForms["set"] = function(args, env) {
157+
if (args.length != 2 || args[0].type != "word")
158+
throw new SyntaxError("Bad use of define");
159+
var proto = Object.getPrototypeOf(env);
160+
var check = false;
161+
while(true) {
162+
if(proto == null) {
163+
if (!check) throw new ReferenceError('ReferenceError hehe');
164+
else break;
165+
}
166+
167+
var value = evaluate(args[1], env);
168+
if(args[0].name in proto) {
169+
env[args[0].name] = value;
170+
check = true;
171+
}
172+
173+
proto = Object.getPrototypeOf(proto);
174+
}
175+
};
176+
177+
var topEnv = Object.create(null);
178+
179+
topEnv["true"] = true;
180+
topEnv["false"] = false;
181+
182+
["+", "-", "*", "/", "==", "<", ">"].forEach(function(op) {
183+
topEnv[op] = new Function("a, b", "return a " + op + " b;");
184+
});
185+
186+
topEnv["print"] = function(value) {
187+
console.log(value);
188+
return value;
189+
};
190+
191+
topEnv["array"] = function(){
192+
return Array.prototype.slice.call(arguments, 0);
193+
}
194+
195+
topEnv["length"] = function(array){
196+
return array.length;
197+
}
198+
199+
topEnv["element"] = function(array, i){
200+
return array[i];
201+
}
202+
203+
var prog = parse("if(true, false, true)");
204+
console.log(evaluate(prog, topEnv));
205+
206+
function run() {
207+
var env = Object.create(topEnv);
208+
var program = Array.prototype.slice
209+
.call(arguments, 0).join("\n");
210+
return evaluate(parse(program), env);
211+
}
212+
213+
run("do(define(total, 0),",
214+
" define(count, 1),",
215+
" while(<(count, 11),",
216+
" do(define(total, +(total, count)),",
217+
" define(count, +(count, 1)))),",
218+
" print(total))");
219+
// → 55
220+
221+
run("do(define(plusOne, fun(a, +(a, 1))),",
222+
" print(plusOne(10)))");
223+
// → 11
224+
225+
run("do(define(pow, fun(base, exp,",
226+
" if(==(exp, 0),",
227+
" 1,",
228+
" *(base, pow(base, -(exp, 1)))))),",
229+
" print(pow(2, 10)))");
230+
// → 1024
231+
232+
// Modify these definitions...
233+
234+
run("do(define(sum, fun(array,",
235+
" do(define(i, 0),",
236+
" define(sum, 0),",
237+
" while(<(i, length(array)),",
238+
" do(define(sum, +(sum, element(array, i))),",
239+
" define(i, +(i, 1)))),",
240+
" sum))),",
241+
" print(sum(array(1, 2, 3))))");
242+
// → 6
243+
244+
run("do(define(f, fun(a, fun(b, +(a, b)))),",
245+
" print(f(4)(5)))");
246+
// → 9
247+
248+
console.log(parse("# hello\nx"));
249+
// → {type: "word", name: "x"}
250+
251+
console.log(parse("a # one\n # two\n()"));
252+
// → {type: "apply",
253+
// operator: {type: "word", name: "a"},
254+
// args: []}
255+
256+
run("do(define(x, 4),",
257+
" define(setx, fun(val, set(x, val))),",
258+
" setx(50),",
259+
" print(x))");
260+
// → 50
261+
262+
run("set(quux, true)");
263+
// → Some kind of ReferenceError

0 commit comments

Comments
(0)

AltStyle によって変換されたページ (->オリジナル) /