diff options
| -rw-r--r-- | shell/eval.mu | 80 | ||||
| -rw-r--r-- | shell/print.mu | 31 |
2 files changed, 99 insertions, 12 deletions
diff --git a/shell/eval.mu b/shell/eval.mu index 211789c8..045d8225 100644 --- a/shell/eval.mu +++ b/shell/eval.mu @@ -162,9 +162,85 @@ fn apply-function params-ah: (addr handle cell), args-ah: (addr handle cell), _b # `out` contains result of evaluating final expression } +# Bind params to corresponding args and add the bindings to old-env. Return +# the result in env-ah. +# +# We never modify old-env, but we point to it. This way other parts of the +# interpreter can continue using old-env, and everything works harmoniously +# even though no cells are copied around. +# +# env should always be a DAG (ignoring internals of values). It doesn't have +# to be a tree (some values may be shared), but there are also no cycles. +# +# Learn more: https://en.wikipedia.org/wiki/Persistent_data_structure fn push-bindings _params-ah: (addr handle cell), _args-ah: (addr handle cell), old-env-h: (handle cell), env-ah: (addr handle cell), trace: (addr trace) { - # no bindings for now - copy-handle old-env-h, env-ah + var params-ah/edx: (addr handle cell) <- copy _params-ah + var args-ah/ebx: (addr handle cell) <- copy _args-ah + var _params/eax: (addr cell) <- lookup *params-ah + var params/esi: (addr cell) <- copy _params + { + var params-is-nil?/eax: boolean <- is-nil? params + compare params-is-nil?, 0/false + break-if-= + # nil is a literal + trace-text trace, "eval", "done with push-bindings" + copy-handle old-env-h, env-ah + trace-higher trace + return + } + # Params can only be symbols or pairs. Args can be anything. + # trace "pushing bindings from " params " to " args {{{ + { + var stream-storage: (stream byte 0x40) + var stream/ecx: (addr stream byte) <- address stream-storage + write stream, "pushing bindings from " + print-cell params-ah, stream, 0/no-trace + write stream, " to " + print-cell args-ah, stream, 0/no-trace + trace trace, "eval", stream + } + # }}} + trace-lower trace + var params-type/eax: (addr int) <- get params, type + compare *params-type, 2/symbol + { + break-if-!= + trace-text trace, "eval", "symbol; binding to all remaining args" + # create a new binding + var new-binding-storage: (handle cell) + var new-binding-ah/eax: (addr handle cell) <- address new-binding-storage + new-pair new-binding-ah, *params-ah, *args-ah + # push it to env + new-pair env-ah, *new-binding-ah, old-env-h + trace-higher trace + return + } + compare *params-type, 0/pair + { + break-if-= + error trace, "cannot bind a non-symbol" + trace-higher trace + return + } + var _args/eax: (addr cell) <- lookup *args-ah + var args/edi: (addr cell) <- copy _args + # params is now a pair, so args must be also + var args-type/eax: (addr int) <- get args, type + compare *args-type, 0/pair + { + break-if-= + error trace, "args not in a proper list" + trace-higher trace + return + } + var intermediate-env-storage: (handle cell) + var intermediate-env-ah/edx: (addr handle cell) <- address intermediate-env-storage + var first-param-ah/eax: (addr handle cell) <- get params, left + var first-arg-ah/ecx: (addr handle cell) <- get args, left + push-bindings first-param-ah, first-arg-ah, old-env-h, intermediate-env-ah, trace + var remaining-params-ah/eax: (addr handle cell) <- get params, right + var remaining-args-ah/ecx: (addr handle cell) <- get args, right + push-bindings remaining-params-ah, remaining-args-ah, *intermediate-env-ah, env-ah, trace } fn apply-primitive _f: (addr cell), args-ah: (addr handle cell), out: (addr handle cell), env-h: (handle cell), trace: (addr trace) { diff --git a/shell/print.mu b/shell/print.mu index 46782705..22c00543 100644 --- a/shell/print.mu +++ b/shell/print.mu @@ -79,16 +79,6 @@ fn print-list _in: (addr cell), out: (addr stream byte), trace: (addr trace) { write out, "(" $print-list:loop: { var left/ecx: (addr handle cell) <- get curr, left - { - var left-addr/eax: (addr cell) <- lookup *left - var left-is-nil?/eax: boolean <- is-nil? left-addr - compare left-is-nil?, 0/false - { - break-if-= - trace-text trace, "print", "left is null" - break $print-list:loop - } - } print-cell left, out, trace var right/ecx: (addr handle cell) <- get curr, right var right-addr/eax: (addr cell) <- lookup *right @@ -251,6 +241,27 @@ fn test-print-cell-list { check-stream-equal out, "(64 abc)", "F - test-print-cell-list" } +fn test-print-cell-list-of-nil { + # list = cons "abc", nil + var left-storage: (handle cell) + var left/ecx: (addr handle cell) <- address left-storage + allocate-pair left + var nil-storage: (handle cell) + var nil/edx: (addr handle cell) <- address nil-storage + allocate-pair nil + var list-storage: (handle cell) + var list/esi: (addr handle cell) <- address list-storage + new-pair list, *left, *nil + # list = cons 64, list + new-integer left, 0x40 + new-pair list, *left, *list + # + var out-storage: (stream byte 0x40) + var out/edi: (addr stream byte) <- address out-storage + print-cell list, out, 0/no-trace + check-stream-equal out, "(64 ())", "F - test-print-cell-list-nil" +} + fn test-print-dotted-list { # list = cons 64, "abc" var left-storage: (handle cell) |