From b6e36923b3106b108b63fe7714292840ae6100e2 Mon Sep 17 00:00:00 2001
From: Gareth Pendleton <gareth.sidebottom@gmail.com>
Date: Thu, 9 Oct 2025 14:01:50 +0100
Subject: [PATCH] feat: Added charref parsing

---
 src/glxml.gleam | 88 ++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 79 insertions(+), 9 deletions(-)

diff --git a/src/glxml.gleam b/src/glxml.gleam
index 1e5c0fb..da1d18d 100644
--- a/src/glxml.gleam
+++ b/src/glxml.gleam
@@ -1,5 +1,6 @@
 import gleam/bool
 import gleam/dict
+import gleam/int
 import gleam/list
 import gleam/option.{type Option, None, Some}
 import gleam/result
@@ -10,7 +11,9 @@ pub type Declaration {
 }
 
 pub type Entity {
-  Entity
+  InternalEntity(value: String)
+  SystemExternalEntity(literal: String)
+  PublicExternalEntity(literal: String, pubidliteral: String)
 }
 
 pub type DocType {
@@ -36,11 +39,21 @@ pub type Element {
 
 pub fn main() {
   parse_document(
-    "<?xml version=\"1.1\" encoding='UTF-8'?>\r\n   <!-- hello-world -->   \n<a attr='haha' battr='baba' ref='&ref;'/>",
+    "<?xml version=\"1.1\" encoding='UTF-8'?>\r\n   <!-- hello-world -->   \n<a attr='ha&#x20;ha' battr='baba' ref='&ref;'/>",
   )
   |> echo
 }
 
+pub fn default_entities() -> dict.Dict(String, Entity) {
+  dict.from_list([
+    #("lt", InternalEntity("&#38;#60;")),
+    #("gt", InternalEntity("#62;")),
+    #("amp", InternalEntity("&#38;#38;")),
+    #("apos", InternalEntity("&#39;")),
+    #("quot", InternalEntity("&#34;")),
+  ])
+}
+
 fn parse_document(doc: String) -> Result(Document, Nil) {
   use #(decl, doctype, doc) <- result.try(parse_prolog(doc))
   use <- bool.guard(when: doc == "", return: Ok(Document(decl, doctype, None)))
@@ -162,7 +175,35 @@ fn parse_reference(
   doctype: Option(DocType),
 ) -> Result(#(String, String), Nil) {
   case doc {
-    "&" as char <> tail | "%" as char <> tail -> {
+    "&#" <> tail -> {
+      case tail {
+        "x" <> tail -> {
+          use #(digits, doc) <- result.try(parse_multiple(tail, parse_hex_digit))
+
+          case doc {
+            ";" <> tail -> {
+              use value <- result.try(int.base_parse(digits, 16))
+              use codepoint <- result.try(string.utf_codepoint(value))
+              Ok(#("", string.from_utf_codepoints([codepoint]) <> tail))
+            }
+            _ -> Error(Nil)
+          }
+        }
+        _ -> {
+          use #(digits, doc) <- result.try(parse_multiple(tail, parse_digit))
+
+          case doc {
+            ";" <> tail -> {
+              use value <- result.try(int.base_parse(digits, 10))
+              use codepoint <- result.try(string.utf_codepoint(value))
+              Ok(#("", string.from_utf_codepoints([codepoint]) <> tail))
+            }
+            _ -> Error(Nil)
+          }
+        }
+      }
+    }
+    "&" as char <> tail -> {
       use #(name, doc) <- result.try(parse_name(tail))
 
       case doc {
@@ -269,7 +310,7 @@ fn do_parse_version(
   doc: String,
   version: String,
 ) -> Result(#(String, String), Nil) {
-  case do_parse_digit(doc) {
+  case parse_digit(doc) {
     Ok(#(digit, doc)) -> do_parse_version(doc, version <> digit)
     Error(_) if version == "" -> Error(Nil)
     Error(_) -> Ok(#(version, doc))
@@ -302,14 +343,14 @@ fn parse_encodingdecl(doc: String) -> Result(#(String, String), Nil) {
 }
 
 fn parse_encoding(doc: String) -> Result(#(String, String), Nil) {
-  case do_parse_alpha(doc) {
+  case parse_alpha(doc) {
     Ok(#(char, doc)) -> {
       Ok(parse_multiple_optional(
         doc,
         try_parsers(
           [
-            do_parse_alpha,
-            do_parse_digit,
+            parse_alpha,
+            parse_digit,
             fn(doc) {
               case doc {
                 "." as char <> tail | "_" as char <> tail | "-" as char <> tail ->
@@ -336,7 +377,7 @@ fn parse_standalone(doc: String) -> Result(#(Bool, String), Nil) {
   }
 }
 
-fn do_parse_digit(doc: String) -> Result(#(String, String), Nil) {
+fn parse_digit(doc: String) -> Result(#(String, String), Nil) {
   case doc {
     "0" as digit <> tail
     | "1" as digit <> tail
@@ -352,7 +393,36 @@ fn do_parse_digit(doc: String) -> Result(#(String, String), Nil) {
   }
 }
 
-fn do_parse_alpha(doc: String) -> Result(#(String, String), Nil) {
+pub fn parse_hex_digit(str: String) -> Result(#(String, String), Nil) {
+  case str {
+    "0" as digit <> tail
+    | "1" as digit <> tail
+    | "2" as digit <> tail
+    | "3" as digit <> tail
+    | "4" as digit <> tail
+    | "5" as digit <> tail
+    | "6" as digit <> tail
+    | "7" as digit <> tail
+    | "8" as digit <> tail
+    | "9" as digit <> tail
+    | "a" as digit <> tail
+    | "b" as digit <> tail
+    | "c" as digit <> tail
+    | "d" as digit <> tail
+    | "e" as digit <> tail
+    | "f" as digit <> tail
+    | "A" as digit <> tail
+    | "B" as digit <> tail
+    | "C" as digit <> tail
+    | "D" as digit <> tail
+    | "E" as digit <> tail
+    | "F" as digit <> tail -> Ok(#(digit, tail))
+
+    _ -> Error(Nil)
+  }
+}
+
+fn parse_alpha(doc: String) -> Result(#(String, String), Nil) {
   case doc {
     "a" as char <> tail
     | "b" as char <> tail