/*
 * Rust code generation for gipfel-rs.
 *
 * Port of gipfel's expr2c.mac (Copyright 2006-2009 Johannes Hofmann).
 * Emits one Rust function per line (grep "^pub fn"); integer literals are
 * converted to float literals by fixup.py afterwards.
 */

load("stringproc")$

varsubst(v) := ssubst("_", "%", string(v))$

printdecl(vars) := (
	sprint("let mut", varsubst(first(vars)), ": f64 = 0.0;"),
	for v in rest(vars) do sprint("let mut", varsubst(v), ": f64 = 0.0;"))$

printdef(expr) := sprint(varsubst(first(expr)), "=", varsubst(second(expr)), ";")$

block2rust(expr) :=
	if ?equal(op(expr), block) then (
		printdecl(first(expr)),
		for d in reverse(rest(reverse(rest(expr)))) do printdef(d),
		sprint("return", varsubst(last(expr)), ";"))
	else
		sprint("return", varsubst(expr), ";")$

expr2rust(funcname, argstr, expr) := (
	sprint("pub fn", funcname, "(", argstr, ") -> f64 {"),
	block2rust(subst(pow, "^", optimize(expr))),
	sprint("}", "
"))$