use linkedhashmap to preserve key order

Author: cscheid

crates/quarto-markdown-pandoc/src/pandoc/meta.rs

@@ -7,7 +7,7 @@ use crate::pandoc::block::Blocks;
 use crate::pandoc::inline::Inlines;
 use crate::readers;
 use crate::{pandoc::RawBlock, utils::output::VerboseOutput};
-use std::collections::HashMap;
+use hashlink::LinkedHashMap;
 use std::{io, mem};
 use yaml_rust2::parser::{Event, MarkedEventReceiver, Parser};
 
@@ -20,16 +20,16 @@ pub enum MetaValue {
     MetaInlines(Inlines),
     MetaBlocks(Blocks),
     MetaList(Vec<MetaValue>),
-    MetaMap(HashMap<String, MetaValue>),
+    MetaMap(LinkedHashMap<String, MetaValue>),
 }
 
 impl Default for MetaValue {
     fn default() -> Self {
-        MetaValue::MetaMap(HashMap::new())
+        MetaValue::MetaMap(LinkedHashMap::new())
     }
 }
 
-pub type Meta = HashMap<String, MetaValue>;
+pub type Meta = LinkedHashMap<String, MetaValue>;
 
 fn extract_between_delimiters(input: &str) -> Option<&str> {
     let parts: Vec<&str> = input.split("---").collect();
@@ -41,7 +41,7 @@ fn extract_between_delimiters(input: &str) -> Option<&str> {
 }
 
 enum ContextFrame {
-    Map(HashMap<String, MetaValue>, Option<String>),
+    Map(LinkedHashMap<String, MetaValue>, Option<String>),
     List(Vec<MetaValue>),
     Root,
 }
@@ -100,7 +100,7 @@ impl MarkedEventReceiver for YamlEventHandler {
         match ev {
             Event::StreamStart | Event::DocumentStart => {}
             Event::MappingStart(..) => {
-                self.stack.push(ContextFrame::Map(HashMap::new(), None));
+                self.stack.push(ContextFrame::Map(LinkedHashMap::new(), None));
             }
             Event::MappingEnd => {
                 if let Some(ContextFrame::Map(map, _)) = self.stack.pop() {

crates/quarto-markdown-pandoc/src/readers/json.rs

@@ -4,17 +4,17 @@
  */
 
 use crate::pandoc::{
-    Attr, Block, BlockQuote, BulletList, Caption, Citation, CitationMode, Cite, Code, CodeBlock, 
-    DefinitionList, Div, Emph, Figure, Header, HorizontalRule, Image, Inline, Inlines, 
-    LineBlock, Link, ListAttributes, ListNumberDelim, ListNumberStyle, Math, MathType, 
-    Meta, MetaValue, Note, OrderedList, Pandoc, Paragraph, Plain, Quoted, QuoteType, 
-    RawBlock, RawInline, SmallCaps, SoftBreak, Space, Span, Str, Strikeout, Strong, 
+    Attr, Block, BlockQuote, BulletList, Caption, Citation, CitationMode, Cite, Code, CodeBlock,
+    DefinitionList, Div, Emph, Figure, Header, HorizontalRule, Image, Inline, Inlines,
+    LineBlock, Link, ListAttributes, ListNumberDelim, ListNumberStyle, Math, MathType,
+    Meta, MetaValue, Note, OrderedList, Pandoc, Paragraph, Plain, Quoted, QuoteType,
+    RawBlock, RawInline, SmallCaps, SoftBreak, Space, Span, Str, Strikeout, Strong,
     Subscript, Superscript, Underline
 };
 use crate::pandoc::block::MetaBlock;
 use crate::pandoc::location::{Range, Location, SourceInfo};
+use hashlink::LinkedHashMap;
 use serde_json::Value;
-use std::collections::HashMap;
 
 #[derive(Debug)]
 pub enum JsonReadError {
@@ -576,12 +576,12 @@ fn read_block(value: &Value) -> Result<Block> {
 
 fn read_meta(value: &Value) -> Result<Meta> {
     let obj = value.as_object().ok_or_else(|| JsonReadError::InvalidType("Expected object for Meta".to_string()))?;
-    
-    let mut meta = HashMap::new();
+
+    let mut meta = LinkedHashMap::new();
     for (key, val) in obj {
         meta.insert(key.clone(), read_meta_value(val)?);
     }
-    
+
     Ok(meta)
 }
 
@@ -617,7 +617,7 @@ fn read_meta_value(value: &Value) -> Result<MetaValue> {
         "MetaMap" => {
             let c = obj.get("c").ok_or_else(|| JsonReadError::MissingField("c".to_string()))?;
             let arr = c.as_array().ok_or_else(|| JsonReadError::InvalidType("MetaMap content must be array".to_string()))?;
-            let mut map = HashMap::new();
+            let mut map = LinkedHashMap::new();
             for item in arr {
                 let kv_arr = item.as_array().ok_or_else(|| JsonReadError::InvalidType("MetaMap item must be array".to_string()))?;
                 if kv_arr.len() != 2 {

crates/quarto-markdown-pandoc/src/writers/qmd.rs

@@ -198,13 +198,9 @@ fn meta_value_to_yaml(value: &MetaValue) -> std::io::Result<Yaml> {
             Ok(Yaml::Array(yaml_list))
         }
         MetaValue::MetaMap(map) => {
-            // Sort keys to ensure deterministic output
-            let mut sorted_keys: Vec<_> = map.keys().collect();
-            sorted_keys.sort();
-
+            // LinkedHashMap preserves insertion order
             let mut yaml_map = LinkedHashMap::new();
-            for key in sorted_keys {
-                let val = &map[key];
+            for (key, val) in map {
                 yaml_map.insert(Yaml::String(key.clone()), meta_value_to_yaml(val)?);
             }
             Ok(Yaml::Hash(yaml_map))
@@ -217,13 +213,9 @@ fn write_meta<T: std::io::Write + ?Sized>(meta: &Meta, buf: &mut T) -> std::io::
         Ok(false)
     } else {
         // Convert Meta to YAML
-        // Sort keys to ensure deterministic output
-        let mut sorted_keys: Vec<_> = meta.keys().collect();
-        sorted_keys.sort();
-
+        // LinkedHashMap preserves insertion order
         let mut yaml_map = LinkedHashMap::new();
-        for key in sorted_keys {
-            let value = &meta[key];
+        for (key, value) in meta {
             yaml_map.insert(Yaml::String(key.clone()), meta_value_to_yaml(value)?);
         }
         let yaml = Yaml::Hash(yaml_map);

crates/quarto-markdown-pandoc/tests/roundtrip_tests/qmd-json-qmd/metadata_key_order.qmd

@@ -0,0 +1,10 @@
+---
+zebra: last
+apple: first
+middle: second
+banana: third
+---
+
+# Test Document
+
+This tests that YAML key order is preserved.

crates/quarto-markdown-pandoc/tests/test_json_roundtrip.rs

@@ -7,13 +7,14 @@ use quarto_markdown_pandoc::pandoc::{Pandoc, Block, Paragraph, Inline, Str};
 use quarto_markdown_pandoc::pandoc::location::SourceInfo;
 use quarto_markdown_pandoc::writers::json;
 use quarto_markdown_pandoc::readers;
+use hashlink::LinkedHashMap;
 use std::collections::HashMap;
 
 #[test]
 fn test_json_roundtrip_simple_paragraph() {
     // Create a simple Pandoc document
     let original = Pandoc {
-        meta: HashMap::new(),
+        meta: LinkedHashMap::new(),
         blocks: vec![Block::Paragraph(Paragraph {
             content: vec![Inline::Str(Str {
                 text: "Hello, world!".to_string(),
@@ -68,7 +69,7 @@ fn test_json_roundtrip_complex_document() {
     // Create a more complex document with multiple block types
     let original = Pandoc {
         meta: {
-            let mut meta = HashMap::new();
+            let mut meta = LinkedHashMap::new();
             meta.insert(
                 "title".to_string(),
                 quarto_markdown_pandoc::pandoc::MetaValue::MetaString("Test Document".to_string())
@@ -182,7 +183,7 @@ fn test_json_write_then_read_matches_original_structure() {
     // with the same basic structure, even if exact equality is not possible
 
     let original = Pandoc {
-        meta: HashMap::new(),
+        meta: LinkedHashMap::new(),
         blocks: vec![
             Block::Plain(quarto_markdown_pandoc::pandoc::Plain {
                 content: vec![Inline::Str(Str {