1 files changed, 91 insertions, 10 deletions
diff --git a/src/libzisp/io/unparser.zig b/src/libzisp/io/unparser.zig
index d835924..c25e918 100644
--- a/src/libzisp/io/unparser.zig
+++ b/src/libzisp/io/unparser.zig
@@ -3,19 +3,100 @@ const std = @import("std");
 const value = @import("../value.zig");
 
 const ShortString = value.ShortString;
+const OtherTag = value.OtherTag;
 const Value = value.Value;
+const Hval = value.Hval;
 
-// const State = struct {
+pub fn unparse(w: anytype, v: Value) anyerror!void {
+    try if (value.double.check(v))
+        unparseDouble(w, v)
+    else if (value.fixnum.check(v))
+        unparseFixnum(w, v)
+    else if (value.ptr.checkZisp(v))
+        unparseHeap(w, v)
+    else
+        unparseOther(w, v);
+}
+
+fn unparseDouble(w: anytype, v: Value) !void {
+    _ = w;
+    _ = v;
+    @panic("not implemented");
+}
+
+fn unparseFixnum(w: anytype, v: Value) !void {
+    _ = w;
+    _ = v;
+    @panic("not implemented");
+}
 
-// }
+fn unparseHeap(w: anytype, v: Value) !void {
+    const p, const t = value.ptr.unpack(v);
+    try switch (t) {
+        .pair => unparsePair(w, p),
+        .istr => @panic("not implemented"),
+        .proc => @panic("not implemented"),
+    };
+}
+
+fn unparseOther(w: anytype, v: Value) !void {
+    try switch (v.other.tag) {
+        .rune => unparseRune(w, v),
+        .sstr => unparseSstr(w, v),
+        .qstr => unparseQstr(w, v),
+        .char => unparseChar(w, v),
+        .misc => unparseMisc(w, v),
+    };
+}
+
+fn unparseRune(w: anytype, v: Value) !void {
+    const name = value.rune.unpack(v);
+    try w.writeByte('#');
+    try w.writeAll(name.constSlice());
+}
 
-pub fn unparse(v: Value) []u8 {
-    var gpa: std.heap.GeneralPurposeAllocator(.{}) = .init;
-    var out: std.ArrayList(u8) = .init(gpa.allocator());
-    if (value.rune.check(v)) {
-        const name = value.rune.unpack(v);
-        out.append('#') catch @panic("");
-        out.appendSlice(name.slice()) catch @panic("");
+fn unparseSstr(w: anytype, v: Value) !void {
+    const str = value.sstr.unpack(v);
+    try w.writeAll(str.constSlice());
+}
+
+fn unparseQstr(w: anytype, v: Value) !void {
+    const str = value.sstr.unpack(v);
+    try w.writeByte('"');
+    try w.writeAll(str.constSlice());
+    try w.writeByte('"');
+}
+
+fn unparseChar(w: anytype, v: Value) !void {
+    var buf: [4]u8 = undefined;
+    const len = try std.unicode.utf8Encode(v.char.value, &buf);
+    try w.writeAll(buf[0..len]);
+}
+
+fn unparseMisc(w: anytype, v: Value) !void {
+    try switch (v.misc.value) {
+        .f => w.writeAll("#f"),
+        .t => w.writeAll("#t"),
+        .nil => w.writeAll("()"),
+        .eof => w.writeAll("#eof"),
+        .undef => w.writeAll("#undef"),
+    };
+}
+
+fn unparsePair(w: anytype, p: [*]Hval) !void {
+    const vs: *[2]Value = @ptrCast(p);
+    try w.writeByte('(');
+    try unparse(w, vs[0]);
+    var cdr = vs[1];
+    while (value.pair.check(cdr)) : (cdr = value.pair.cdr(cdr)) {
+        try w.writeByte(' ');
+        try unparse(w, value.pair.car(cdr));
+    }
+    if (!value.nil.check(cdr)) {
+        try w.writeByte(' ');
+        try w.writeByte('.');
+        try w.writeByte(' ');
+        try unparse(w, cdr);
     }
-    return out.toOwnedSlice() catch @panic("");
+    try w.writeByte(')');
 }