a

1 files changed, 33 insertions, 0 deletions

diff --git a/examples/staged.zc b/examples/staged.zc
new file mode 100644
index 0000000..a180ae3
--- /dev/null
+++ b/examples/staged.zc
@@ -0,0 +1,33 @@
+// staged code: a program writes a specialized function as source, compiles it
+// while running, and calls it. here, polynomials with their coefficients baked
+// in as constants, so there's no loop and no array left at runtime.
+let buf[2000], n;
+fn put(s) { let i = 0; while (s[i]) { buf[n] = s[i]; n++; i++; } return 0; }
+fn putnum(int v) { if (v >= 10) putnum(v / 10); buf[n] = '0' + v % 10; n++; return 0; }
+
+// coefficients c[0] + c[1] x + ... in horner form: ((c3 x + c2) x + c1) x + c0
+fn specialize(int* c, int deg) {
+	n = 0;
+	put("fn poly(x) { return ");
+	for (int i = 0; i < deg; i++) put("(");
+	if (c[deg] < 0) { put("0 - "); putnum(0 - c[deg]); } else putnum(c[deg]);
+	for (int i = deg - 1; i >= 0; i--) {
+		put(") * x ");
+		if (c[i] < 0) { put("- "); putnum(0 - c[i]); } else { put("+ "); putnum(c[i]); }
+	}
+	put("; }");
+	buf[n] = 0;
+	return buf;
+}
+fn main() {
+	[4]int c;
+	c[0] = 7; c[1] = 0 - 3; c[2] = 0; c[3] = 2;	// 2x^3 - 3x + 7
+	let src = specialize(c, 3), q = tokens(src);
+	put_s(src); put_c(10);
+	load(q);			// compiled now, into the running program
+	free(d*q);
+	let f = sval[lookups("poly")];	// and found by name in the compiler's symbol table
+	for (int x = 0 - 2; x <= 3; x++) { put_n(f(x)); put_c(' '); }
+	put_c(10);
+	return 0;
+}