static void TestCustomExterns()
{
// Create an evaluator with custom defined functions:
var ev = new Evaluator()
{
{ "str", (v, e) => v.Eval(e[0]).ToString() },
{ "qualify", (v, e) =>
{
if (e.Count != 2) throw new ArgumentException("qualify requires 2 parameters");
// Evaluate parameters:
var prefix = v.EvalExpecting<string>(e[0]);
var list = v.EvalExpecting<object[]>(e[1]);
var sb = new StringBuilder();
for (int i = 0; i < list.Length; ++i)
{
if (list[i].GetType() != typeof(string)) throw new ArgumentException("list item {0} must evaluate to a string".F(i + 1));
sb.AppendFormat("[{0}].[{1}]", prefix, (string)list[i]);
if (i < list.Length - 1) sb.Append(", ");
}
return sb.ToString();
} },
{ "prefix", (v, e) =>
{
if (e.Count != 2) throw new ArgumentException("prefix requires 2 parameters");
// Evaluate parameters:
var prefix = v.EvalExpecting<string>(e[0]);
var list = v.EvalExpecting<object[]>(e[1]);
var sb = new StringBuilder();
for (int i = 0; i < list.Length; ++i)
{
if (list[i].GetType() != typeof(string)) throw new ArgumentException("list item {0} must evaluate to a string".F(i + 1));
sb.AppendFormat("[{0}].[{1}] AS [{0}_{1}]", prefix, (string)list[i]);
if (i < list.Length - 1) sb.Append(", ");
}
return sb.ToString();
} }
};
// Run through some test cases:
{
const string code = @"{prefix st [StudentID FirstName LastName]}";
var prs = new Parser(new Lexer(new StringReader(code)));
var expr = prs.ParseExpr();
// Evaluate and output:
var result = ev.Eval(expr);
Output(result);
Console.WriteLine();
}
}
static void Main(string[] args)
{
// With apologies to Philip Greenspun.
string[] badCodes = new string[]
{
// All should error:
@"",
@"(",
@")",
@"[",
@"]",
@"'",
@"'\'",
@"'\b'",
@"(true)",
@"(null)",
@"(())",
@"([] ())",
@"~",
@"-",
@"(.ToString null)",
};
string[] goodCodes = new string[]
{
// All should succeed:
@"true",
@"false",
@"null",
@"'test'",
@"~(if true true false)",
@"(eval ~(if true true false))",
@"(if true 'hello' 'world')",
@"(if false 'hello' 'world')",
@"(if (eq true false) true false)",
@"(if (eq false false) true false)",
@"(if (eq false false) true null)",
@"(if (eq null null) true null)",
@"(if (ne true false) true false)",
@"(if (ne false false) true false)",
@"(if (ne false false) true false)",
@"(if (ne null null) true false)",
@"'hello
world'",
@"'hello\nworld'",
@"'hello\t\rworld'",
@"'hello \'world\''",
@"'hello ""world""'",
@"`multiline
raw
string literal with ""quotes"" inside
it and 'quotes' too.
<html> is possible here.`",
@"~'test'",
@"~1.34",
@"~1.34d",
@"~1.34f",
@"1.333333333333333333333333333333333333",
@"1.333333333333333333333333333333333333d",
@"1.333333333333333333333333333333333333f",
@"1",
@"008",
@"-1",
@"[10 -3]",
// NOTE(jsd): Currently, whitespace separators are ignored for parsing purposes. This is subject to change.
@"(.ToString (System.DateTime/Now) 'yyyyMMdd')",
@"(. ToString (System . DateTime/Now) 'yyyyMMdd')",
@"(.ToString (System. DateTime / Now) 'yyyyMMdd')",
// TODO: add, inc, dec functions and possibly other basics:
//@"(add x y)",
//@"(inc 1)",
//@"(dec 1)",
// TODO: let with scoping
//@"(let [x 1, y 2] (add x y))",
};
{
int pass = 0, fail = 0;
// Test the bad codes which should always fail:
for (int i = 0; i < badCodes.Length; ++i)
{
string code = badCodes[i];
try
{
var prs = new Parser(new Lexer(new StringReader(code)));
var expr = prs.ParseExpr();
// Evaluate:
var ev = new Evaluator();
var result = ev.Eval(expr);
// Failed! Should've gotten some sort of exception.
++fail;
}
catch (Exception)
{
++pass;
}
}
Console.WriteLine("{0,3}/{1,3} failure tests passed", pass, pass + fail);
}
{
int pass = 0, fail = 0;
// Test the good codes which should always pass:
for (int i = 0; i < goodCodes.Length; ++i)
{
Console.WriteLine();
string code = goodCodes[i];
try
{
Console.ForegroundColor = ConsoleColor.Red;
Console.Write("[{0,3}]: ", i);
Console.ForegroundColor = ConsoleColor.Cyan;
Console.WriteLine(code);
var prs = new Parser(new Lexer(new StringReader(code)));
var expr = prs.ParseExpr();
// Output the s-expression:
var sb = new StringBuilder();
Console.Write(" ");
Console.WriteLine(expr.AppendTo(sb).ToString());
Console.ForegroundColor = ConsoleColor.Red;
Console.Write(" => ");
Console.ForegroundColor = ConsoleColor.White;
// Evaluate and output:
var ev = new Evaluator();
var result = ev.Eval(expr);
++pass;
Output(result);
}
catch (Exception ex)
{
++fail;
Console.ForegroundColor = ConsoleColor.Yellow;
Console.Write(ex);
Console.ForegroundColor = ConsoleColor.White;
}
Console.WriteLine();
}
Console.WriteLine("{0,3}/{1,3} success tests passed", pass, pass + fail);
}
}