dc

commit cbb5cc555b6dcaed9f5740c33ff3d309721dfd18
parent 44c38c222b23f23563dc9c9b2d9399d89e32621f
Author: Byron Torres <b@torresjrjr.com>
Date:   Tue, 23 Nov 2021 00:07:58 +0000

scan numbers

Diffstat:
M
dc.ha
 | 
76
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++----------------

1 file changed, 60 insertions(+), 16 deletions(-)
diff --git a/dc.ha b/dc.ha
@@ -1,3 +1,4 @@
+use ascii;
 use bufio;
 use encoding::utf8;
 use fmt;
@@ -5,6 +6,7 @@ use getopt;
 use io;
 use os;
 use strconv;
+use strings;
 
 let stack: []f64 = [];
 
@@ -44,38 +46,36 @@ export fn main() void = {
 			yield r;
 		};
 
+		if (ascii::isdigit(r)) {
+			bufio::unreadrune(os::stdin, r);
+			const el = scan_number();
+			push(el);
+			continue;
+		};
+
 		switch (r) {
-		case '1' =>
-			const el = 1f64;
-			append(stack, el);
 		case '+' =>
 			if (len(stack) < 2) {
 				fmt::errorln("dc: stack has too few elements")?;
 				continue;
 			};
-			const a = stack[len(stack) - 2];
-			const b = stack[len(stack) - 1];
-			const sum = a + b;
-			delete(stack[len(stack) - 1]);
-			delete(stack[len(stack) - 1]);
-			append(stack, sum);
+			const a = pop();
+			const b = pop();
+			push(a + b);
 		case '-' =>
 			if (len(stack) < 2) {
 				fmt::errorln("dc: stack has too few elements")?;
 				continue;
 			};
-			const a = stack[len(stack) - 2];
-			const b = stack[len(stack) - 1];
-			const diff = a - b;
-			delete(stack[len(stack) - 1]);
-			delete(stack[len(stack) - 1]);
-			append(stack, diff);
+			const a = pop();
+			const b = pop();
+			push(a - b);
 		case 'p' =>
 			if (len(stack) == 0) {
 				fmt::errorln("dc: stack has no elements")?;
 				continue;
 			};
-			const el = stack[len(stack) - 1];
+			const el = peek();
 			fmt::println(el)?;
 		case =>
 			continue;
@@ -87,3 +87,47 @@ export fn main() void = {
 	getopt::printusage(os::stderr, os::args[0], help);
 	os::exit(1);
 };
+
+fn scan_number() f64 = {
+	let num: []u8 = [];
+	defer free(num);
+	for (true) {
+		const r = match (bufio::scanrune(os::stdin)) {
+		case utf8::invalid =>
+			fmt::fatal("dc: invalid utf8 input");
+		case io::error =>
+			fmt::fatal("dc: IO error");
+		case io::EOF =>
+			yield ' ';
+		case r: rune =>
+			yield r;
+		};
+
+		if (ascii::isdigit(r)) {
+			append(num, r: u32: u8);
+		} else {
+			bufio::unreadrune(os::stdin, r);
+			match (strconv::stof64(strings::fromutf8(num))) {
+			case (strconv::invalid | strconv::overflow) =>
+				abort("dc: invalid numerical input");
+			case n: f64 =>
+				return n;
+			};
+		};
+	};
+	abort("Unreachable");
+};
+
+fn pop() f64 = {
+	const a = stack[len(stack) - 1];
+	delete(stack[len(stack) - 1]);
+	return a;
+};
+
+fn push(el: f64) void = {
+	append(stack, el);
+};
+
+fn peek() f64 = {
+	return stack[len(stack) - 1];
+};