| One frontend where there were three, and a core that is not Clojure 438b247 nandi yesterday | 1 | ## The C ABI, and nothing else. |
| 2 | ## |
| 3 | ## Every exported symbol is here so there is one file to read when asking what |
| 4 | ## the Dart side can call. The logic lives under `frq/` in ordinary Nim with |
| 5 | ## ordinary Nim types, which is what lets the tests test the rules rather than |
| 6 | ## the marshalling. |
| 7 | ## |
| 8 | ## Two conventions, both of which the bindings in `flutter/src/frq/core/` |
| 9 | ## wrap so no call site has to remember them: |
| 10 | ## |
| 11 | ## * Every returned string is the **caller's** to free, with `frq_free`. Nim's |
| 12 | ## allocator is not Dart's, so a `free()` on this side of the boundary is |
| 13 | ## undefined behaviour rather than a leak you can live with. |
| 14 | ## * `frq_init` runs once before anything else. Nim's runtime needs setting up |
| 15 | ## and `--app:lib` does not do it for you on every platform. |
| 16 | ## |
| 17 | ## Answers that are not a single string come back as JSON. A struct would mean |
| 18 | ## both sides agreeing on a memory layout, and a field added later would be a |
| 19 | ## version skew that segfaults rather than one that fails; JSON costs a parse |
| 20 | ## per call, which is nothing against the network round trip that produced the |
| 21 | ## line being parsed. |
| 22 | |
| 23 | import std/json |
| A message in #test, from Nim 35994d4 nandi 23h ago | 24 | import frq/[ircparse, ui, state, irc] |
| Nim under the existing UI, not instead of it 56551a8 nandi 22h ago | 25 | import frq/conn as tr |
| 26 | import frq/trace |
| Nim owns the screen, Dart owns the pixels 43a02c2 nandi 23h ago | 27 | import frq/screens/connect as connectScreen |
| A message in #test, from Nim 35994d4 nandi 23h ago | 28 | import frq/screens/chat as chatScreen |
| One frontend where there were three, and a core that is not Clojure 438b247 nandi yesterday | 29 | |
| 30 | proc NimMain() {.importc.} |
| 31 | |
| 32 | var initialised = false |
| 33 | |
| 34 | proc frq_init*() {.exportc, dynlib.} = |
| 35 | ## Set Nim's runtime up. Idempotent, because a binding that guesses wrong |
| 36 | ## about whether it has been called should be harmless rather than fatal. |
| 37 | if not initialised: |
| 38 | NimMain() |
| 39 | initialised = true |
| 40 | |
| 41 | proc dup(s: string): cstring = |
| 42 | ## A copy of `s` that outlives this call, for the caller to `frq_free`. |
| 43 | ## `allocShared0` and not `alloc0`: the Dart side may free it from a |
| 44 | ## different thread than the one that made it. |
| 45 | let n = s.len |
| 46 | let p = cast[cstring](allocShared0(n + 1)) |
| 47 | if n > 0: |
| 48 | copyMem(p, unsafeAddr s[0], n) |
| 49 | p |
| 50 | |
| 51 | proc frq_free*(p: cstring) {.exportc, dynlib.} = |
| 52 | ## Free what one of the functions below returned. Null is fine. |
| 53 | if p != nil: |
| 54 | deallocShared(p) |
| 55 | |
| 56 | proc frq_version*(): cstring {.exportc, dynlib.} = |
| 57 | ## Static storage, deliberately: this one is NOT freed, and is the only |
| 58 | ## exception to the rule above. It exists so a binding can check at load |
| 59 | ## time that the library it found is the one it was built against. |
| 60 | "0.1.0" |
| 61 | |
| 62 | # ----------------------------------------------------------------- irc/parse |
| 63 | |
| 64 | proc frq_irc_parse_line*(line: cstring): cstring {.exportc, dynlib.} = |
| 65 | ## An IRC line as JSON: `{raw, tags, account, prefix, command, params}`. |
| 66 | ## |
| 67 | ## `tags`, `account` and `prefix` are JSON null where the line carried none, |
| 68 | ## which is the distinction `frq.irc.parse` draws with nil and every caller |
| 69 | ## of it depends on — a PRIVMSG from a server with no prefix is not the same |
| 70 | ## line as one from a nick. |
| 71 | if line == nil: return dup("null") |
| 72 | let p = parseLine($line) |
| 73 | var o = newJObject() |
| 74 | o["raw"] = %p.raw |
| 75 | o["tags"] = if p.hasTags: %p.tags else: newJNull() |
| 76 | o["account"] = if p.hasAccount: %p.account else: newJNull() |
| 77 | o["prefix"] = if p.hasPrefix: %p.prefix else: newJNull() |
| 78 | o["command"] = %p.command |
| 79 | o["params"] = %p.params |
| 80 | dup($o) |
| 81 | |
| 82 | proc frq_irc_tag_value*(tags, key: cstring): cstring {.exportc, dynlib.} = |
| 83 | ## One tag's value, unescaped — or **null** where the tag is absent or |
| 84 | ## empty, which IRCv3 says are the same thing. Null and not "" on purpose: |
| 85 | ## see `tagValue`. |
| 86 | if tags == nil or key == nil: return nil |
| 87 | let (v, ok) = tagValue($tags, $key) |
| 88 | if ok: dup(v) else: nil |
| 89 | |
| 90 | proc frq_irc_unescape_tag*(v: cstring): cstring {.exportc, dynlib.} = |
| 91 | if v == nil: return nil |
| 92 | dup(unescapeTag($v)) |
| 93 | |
| 94 | proc frq_irc_escape_tag_value*(v: cstring): cstring {.exportc, dynlib.} = |
| 95 | if v == nil: return dup("") |
| 96 | dup(escapeTagValue($v)) |
| 97 | |
| 98 | proc frq_irc_nick_of*(prefix: cstring): cstring {.exportc, dynlib.} = |
| 99 | if prefix == nil: return nil |
| 100 | dup(nickOf($prefix)) |
| Nim owns the screen, Dart owns the pixels 43a02c2 nandi 23h ago | 101 | |
| 102 | # ------------------------------------------------------------------- the UI |
| 103 | # |
| 104 | # The spike's real claim: Nim owns the state and the screen, Dart owns the |
| 105 | # pixels, and the only things crossing are a tree going out and an event id |
| 106 | # coming back. See `frq/ui.nim`. |
| 107 | |
| A message in #test, from Nim 35994d4 nandi 23h ago | 108 | proc currentTree(): string = |
| The window connects 1d62d1a nandi 23h ago | 109 | maybeAutoconnect() |
| A message in #test, from Nim 35994d4 nandi 23h ago | 110 | ## Whichever screen the state says. `drain` first, so the tree Dart gets is |
| 111 | ## built after every line that had arrived when it asked — that is the whole |
| 112 | ## of the polling model, and it is why there is no callback into Dart. |
| 113 | drain() |
| 114 | case app.screen |
| 115 | of scChat: $chatScreen.chatScreen(app).toJson |
| 116 | else: $connectScreen.connectScreen(app).toJson |
| 117 | |
| Nim owns the screen, Dart owns the pixels 43a02c2 nandi 23h ago | 118 | proc frq_ui_render*(): cstring {.exportc, dynlib.} = |
| A message in #test, from Nim 35994d4 nandi 23h ago | 119 | ## The current screen as a widget tree, in JSON. |
| 120 | ## |
| 121 | ## No longer pure, and the change is worth naming: it drains the socket's |
| 122 | ## queue first, so two calls with no dispatch between can differ when a line |
| 123 | ## arrived in the gap. That is the point — it is how the room fills — but it |
| 124 | ## means the renderer must be free to call this whenever it likes, which is |
| 125 | ## what the Dart side's poll timer does. |
| 126 | dup(currentTree()) |
| Nim owns the screen, Dart owns the pixels 43a02c2 nandi 23h ago | 127 | |
| 128 | proc frq_ui_dispatch*(event: cstring): cstring {.exportc, dynlib.} = |
| 129 | ## Apply an event and answer with the tree it produced. |
| 130 | ## |
| 131 | ## One call rather than dispatch-then-render, and not to save a crossing: |
| 132 | ## it makes the pair atomic. Two calls leave a window in which Dart could |
| 133 | ## render a state nothing asked for, which is the sort of thing that shows |
| 134 | ## up once a week and never in a test. |
| 135 | ## |
| 136 | ## A malformed event is ignored rather than fatal — it arrives from a tree |
| 137 | ## the renderer may have been holding for a frame, which is a normal race. |
| 138 | if event != nil: |
| 139 | try: |
| 140 | dispatch(parseJson($event)) |
| 141 | except JsonParsingError: |
| 142 | discard |
| A message in #test, from Nim 35994d4 nandi 23h ago | 143 | dup(currentTree()) |
| 144 | |
| 145 | proc frq_ui_poll*(): cstring {.exportc, dynlib.} = |
| 146 | ## The tree, for a renderer that is asking because time passed rather than |
| 147 | ## because anything happened. Identical to `frq_ui_render` — named |
| 148 | ## separately so the Dart side reads as what it means. |
| 149 | dup(currentTree()) |
| 150 | |
| 151 | proc frq_ui_offline*() {.exportc, dynlib.} = |
| 152 | ## Stop `connect` from opening a socket, for a test that wants the screens |
| 153 | ## without the network. There is no way back — a process that has asked for |
| 154 | ## this is a test process. |
| 155 | goOffline() |
| Nim owns the screen, Dart owns the pixels 43a02c2 nandi 23h ago | 156 | |
| 157 | proc frq_ui_reset*() {.exportc, dynlib.} = |
| 158 | ## Back to a fresh state. For tests, and for a renderer that wants a known |
| 159 | ## starting point rather than whatever the last run left. |
| A message in #test, from Nim 35994d4 nandi 23h ago | 160 | irc.stop() |
| Nim owns the screen, Dart owns the pixels 43a02c2 nandi 23h ago | 161 | app = initState() |
| Nim under the existing UI, not instead of it 56551a8 nandi 22h ago | 162 | |
| 163 | |
| 164 | # --------------------------------------------------------------- transport |
| 165 | # |
| 166 | # `frq.net`'s three operations, for `frq.net.nim` to install. This is the |
| 167 | # wiring that matters: the existing ClojureDart screens, cells and actions are |
| 168 | # untouched, and only the socket underneath them becomes Nim. |
| 169 | # |
| 170 | # Polled rather than callback-driven, for the reason the UI is: a Dart callback |
| 171 | # invoked from a foreign thread has to be marshalled onto the main isolate, and |
| 172 | # a timer on the Dart side does the same job with no mechanism at all. |
| 173 | |
| 174 | proc frq_trace*(topic, msg: cstring) {.exportc, dynlib.} = |
| 175 | ## Let the Dart side log through the same facility, so one FRQ_TRACE=1 gives |
| 176 | ## one interleaved story instead of two half-ones in different places. |
| 177 | if topic != nil and msg != nil: |
| 178 | trace($topic, $msg) |
| 179 | |
| 180 | proc frq_conn_open*(host: cstring, port: cint, tls: cint) {.exportc, dynlib.} = |
| 181 | if host == nil: return |
| 182 | tr.open(tr.ConnConfig(host: $host, port: port.int, tls: tls != 0)) |
| 183 | |
| 184 | proc frq_conn_send*(line: cstring) {.exportc, dynlib.} = |
| 185 | if line != nil: tr.send($line) |
| 186 | |
| 187 | proc frq_conn_close*() {.exportc, dynlib.} = |
| 188 | tr.close() |
| 189 | |
| 190 | proc frq_conn_recv*(): cstring {.exportc, dynlib.} = |
| 191 | ## The next line, or null when there is none waiting. Never blocks. |
| 192 | let (ok, line) = tr.tryLine() |
| 193 | if ok: dup(line) else: nil |
| 194 | |
| 195 | proc frq_conn_event*(): cstring {.exportc, dynlib.} = |
| 196 | ## The next transport event — "open", "close: …", "error: …" — or null. |
| 197 | let (ok, e) = tr.tryEvent() |
| 198 | if ok: dup(e) else: nil |