From f072525dd41d2f1d81755b89c1dec1ed9cb54101 Mon Sep 17 00:00:00 2001
From: Emery Hemingway <ehmry@posteo.net>
Date: Sat, 20 Jan 2024 15:28:36 +0200
Subject: [PATCH] syndesizer: add XML translator

---
 README.md                         | 20 +++++++++++++++++++
 assertions.prs                    |  2 ++
 config.prs                        |  4 ++++
 src/schema/assertions.nim         |  8 ++++++--
 src/schema/config.nim             |  8 ++++++++
 src/syndesizer.nim                |  4 +++-
 src/syndesizer/xml_translator.nim | 33 +++++++++++++++++++++++++++++++
 syndicate_utils.nimble            |  2 +-
 8 files changed, 77 insertions(+), 4 deletions(-)
 create mode 100644 src/syndesizer/xml_translator.nim

diff --git a/README.md b/README.md
index 2db3392..8d97b1b 100644
--- a/README.md
+++ b/README.md
@@ -249,6 +249,26 @@ $websocketspace ? <connected $websocketUrl> [
   <bind <ref { oid: "websocket" key: #x"" }> $websocketspace #f>
 ]
 ```
+### XML translator
+
+Translates between Preserves and XML according to the [Conventions for Common Data Types](https://preserves.dev/conventions.html).
+
+Examples:
+- `<xml-translation "<foo a=\"1\"> <bar>hello world!</bar></foo>" <foo {"a": 1}<bar "hello world!">>>`
+- `<xml-translation "" [#t #f]>`
+- `<xml-translation "<<</>>" #f>`
+
+```
+# Configuration example
+? <sharedspace ?ds> [
+  $ds ? <Observe <rec xml-translation _> _> $config [
+    $config <require-service <daemon syndesizer>>
+    $config ? <service-object <daemon syndesizer> ?cap> [
+      $cap <xml-translator { dataspace: $ds }>
+    ]
+  ]
+]
+```
 
 ---
 
diff --git a/assertions.prs b/assertions.prs
index ed283c4..158d2fb 100644
--- a/assertions.prs
+++ b/assertions.prs
@@ -6,3 +6,5 @@ FileSystemUsage = <file-system-usage @path string @size int>.
 # an exception for <Observe …> which is pulsed every periodSec.
 # The pulse resolution is no more than one millisecond.
 Pulse = <pulse @periodSec double @proxy #!any>.
+
+XmlTranslation = <xml-translation @xml string @pr any>.
diff --git a/config.prs b/config.prs
index fad1099..ca5e4a2 100644
--- a/config.prs
+++ b/config.prs
@@ -47,5 +47,9 @@ WebsocketArguments = <websocket {
   url: string
 }>.
 
+XmlTranslatorArguments = <xml-translator {
+  dataspace: #!any
+}>.
+
 # Reused from syndicate-protocols/transportAddress
 Tcp = <tcp @host string @port int>.
diff --git a/src/schema/assertions.nim b/src/schema/assertions.nim
index d43905c..afdbd85 100644
--- a/src/schema/assertions.nim
+++ b/src/schema/assertions.nim
@@ -7,12 +7,16 @@ type
     `periodSec`*: float64
     `proxy`* {.preservesEmbedded.}: Value
 
+  XmlTranslation* {.preservesRecord: "xml-translation".} = object
+    `xml`*: string
+    `pr`*: Value
+
   FileSystemUsage* {.preservesRecord: "file-system-usage".} = object
     `path`*: string
     `size`*: BiggestInt
 
-proc `$`*(x: Pulse | FileSystemUsage): string =
+proc `$`*(x: Pulse | XmlTranslation | FileSystemUsage): string =
   `$`(toPreserves(x))
 
-proc encode*(x: Pulse | FileSystemUsage): seq[byte] =
+proc encode*(x: Pulse | XmlTranslation | FileSystemUsage): seq[byte] =
   encode(toPreserves(x))
diff --git a/src/schema/config.nim b/src/schema/config.nim
index 421cbe5..3230a6d 100644
--- a/src/schema/config.nim
+++ b/src/schema/config.nim
@@ -54,6 +54,12 @@ type
   CacheArguments* {.preservesRecord: "cache".} = object
     `field0`*: CacheArgumentsField0
 
+  XmlTranslatorArgumentsField0* {.preservesDictionary.} = object
+    `dataspace`* {.preservesEmbedded.}: EmbeddedRef
+
+  XmlTranslatorArguments* {.preservesRecord: "xml-translator".} = object
+    `field0`*: XmlTranslatorArgumentsField0
+
   PostgreConnectionParameter* {.preservesTuple.} = object
     `key`*: string
     `val`*: string
@@ -82,6 +88,7 @@ proc `$`*(x: WebsocketArguments | JsonTranslatorArguments |
     FileSystemUsageArguments |
     SqliteArguments |
     CacheArguments |
+    XmlTranslatorArguments |
     PostgreConnectionParameter |
     PostgreArguments |
     PulseArguments |
@@ -95,6 +102,7 @@ proc encode*(x: WebsocketArguments | JsonTranslatorArguments |
     FileSystemUsageArguments |
     SqliteArguments |
     CacheArguments |
+    XmlTranslatorArguments |
     PostgreConnectionParameter |
     PostgreArguments |
     PulseArguments |
diff --git a/src/syndesizer.nim b/src/syndesizer.nim
index 79871df..66b489e 100644
--- a/src/syndesizer.nim
+++ b/src/syndesizer.nim
@@ -16,7 +16,8 @@ import ./syndesizer/[
   json_translator,
   pulses,
   webhooks,
-  websockets]
+  websockets,
+  xml_translator]
 
 when withPostgre:
   import ./syndesizer/postgre_actor
@@ -34,6 +35,7 @@ runActor("syndesizer") do (turn: var Turn; root: Cap):
   discard spawnPulseActor(turn, root)
   discard spawnWebhookActor(turn, root)
   discard spawnWebsocketActor(turn, root)
+  discard spawnXmlTranslator(turn, root)
   when withPostgre:
     discard spawnPostgreActor(turn, root)
   when withSqlite:
diff --git a/src/syndesizer/xml_translator.nim b/src/syndesizer/xml_translator.nim
new file mode 100644
index 0000000..24fdd12
--- /dev/null
+++ b/src/syndesizer/xml_translator.nim
@@ -0,0 +1,33 @@
+# SPDX-FileCopyrightText: ☭ Emery Hemingway
+# SPDX-License-Identifier: Unlicense
+
+import std/[options, parsexml, xmlparser, xmltree]
+import preserves, preserves/xmlhooks
+import syndicate
+
+import ../schema/[assertions, config]
+
+proc translateXml(s: string): XmlTranslation =
+  result.xml = s
+  try: result.pr = result.xml.parseXml({allowUnquotedAttribs}).toPreservesHook
+  except XmlError: discard
+
+proc translatePreserves(pr: Value): XmlTranslation {.gcsafe.} =
+  result.pr = pr
+  var xn = result.pr.preservesTo(XmlNode)
+  if xn.isSome: result.xml = $get(xn)
+
+proc spawnXmlTranslator*(turn: var Turn; root: Cap): Actor {.discardable.} =
+  spawn("xml-translator", turn) do (turn: var Turn):
+    during(turn, root, ?:XmlTranslatorArguments) do (ds: Cap):
+      let obsPat = ?Observe(pattern: !XmlTranslation)
+      during(turn, ds, obsPat ?? {0: grab()}) do (xs: Literal[string]):
+        publish(turn, ds, translateXml(xs.value))
+      during(turn, ds, obsPat ?? {1: grab()}) do (pr: Literal[Value]):
+        publish(turn, ds, translatePreserves(pr.value))
+
+when isMainModule:
+  import syndicate/relays
+  runActor("main") do (turn: var Turn; root: Cap):
+    connectStdio(turn, root)
+    spawnXmlTranslator(turn, root)
diff --git a/syndicate_utils.nimble b/syndicate_utils.nimble
index c86caf3..a419894 100644
--- a/syndicate_utils.nimble
+++ b/syndicate_utils.nimble
@@ -1,6 +1,6 @@
 # Package
 
-version = "20240118"
+version = "20240120"
 author        = "Emery Hemingway"
 description   = "Utilites for Syndicated Actors and Synit"
 license       = "unlicense"