From e4014b2138267a3eea131e11284628a313db2235 Mon Sep 17 00:00:00 2001
From: Lars Wirzenius <liw@liw.fi>
Date: Wed, 26 Oct 2022 11:29:06 +0300
Subject: feat: store start location of each element

Sponsored-by: author
---
 src/html.rs | 54 +++++++++++++++++++++++++++++++++++++-----------------
 1 file changed, 37 insertions(+), 17 deletions(-)

diff --git a/src/html.rs b/src/html.rs
index abbe71d..6605333 100644
--- a/src/html.rs
+++ b/src/html.rs
@@ -73,9 +73,11 @@ pub fn parse(markdown: &str) -> Result<Element, SiteError> {
     stack.push(Element::new(ElementTag::Body));
     for (event, loc) in p {
         trace!("event {:?}", event);
+        let (line, col) = linecol.get(loc.start);
+        let loc = Location::new(line, col);
         match event {
             Event::Start(tag) => match tag {
-                Tag::Paragraph => stack.push_tag(ElementTag::P),
+                Tag::Paragraph => stack.push_tag(ElementTag::P, loc),
                 Tag::Heading(level, id, classes) => {
                     let tag = match level {
                         HeadingLevel::H1 => ElementTag::H1,
@@ -101,23 +103,23 @@ pub fn parse(markdown: &str) -> Result<Element, SiteError> {
                     }
                     stack.push(h);
                 }
-                Tag::BlockQuote => stack.push_tag(ElementTag::Blockquote),
-                Tag::CodeBlock(_) => stack.push_tag(ElementTag::Pre),
-                Tag::List(None) => stack.push_tag(ElementTag::Ul),
+                Tag::BlockQuote => stack.push_tag(ElementTag::Blockquote, loc),
+                Tag::CodeBlock(_) => stack.push_tag(ElementTag::Pre, loc),
+                Tag::List(None) => stack.push_tag(ElementTag::Ul, loc),
                 Tag::List(Some(start)) => {
-                    let mut e = Element::new(ElementTag::Ol);
+                    let mut e = Element::new(ElementTag::Ol).with_location(loc);
                     e.push_attribute(Attribute::new("start", &format!("{}", start)));
                     stack.push(e);
                 }
-                Tag::Item => stack.push_tag(ElementTag::Li),
+                Tag::Item => stack.push_tag(ElementTag::Li, loc),
                 Tag::FootnoteDefinition(_) => unreachable!("{:?}", tag),
-                Tag::Table(_) => stack.push_tag(ElementTag::Table),
-                Tag::TableHead => stack.push_tag(ElementTag::Th),
-                Tag::TableRow => stack.push_tag(ElementTag::Tr),
-                Tag::TableCell => stack.push_tag(ElementTag::Td),
-                Tag::Emphasis => stack.push_tag(ElementTag::Em),
-                Tag::Strong => stack.push_tag(ElementTag::Strong),
-                Tag::Strikethrough => stack.push_tag(ElementTag::Del),
+                Tag::Table(_) => stack.push_tag(ElementTag::Table, loc),
+                Tag::TableHead => stack.push_tag(ElementTag::Th, loc),
+                Tag::TableRow => stack.push_tag(ElementTag::Tr, loc),
+                Tag::TableCell => stack.push_tag(ElementTag::Td, loc),
+                Tag::Emphasis => stack.push_tag(ElementTag::Em, loc),
+                Tag::Strong => stack.push_tag(ElementTag::Strong, loc),
+                Tag::Strikethrough => stack.push_tag(ElementTag::Del, loc),
                 Tag::Link(_, url, title) => {
                     let mut link = Element::new(ElementTag::A);
                     link.push_attribute(Attribute::new("href", url.as_ref()));
@@ -142,8 +144,7 @@ pub fn parse(markdown: &str) -> Result<Element, SiteError> {
                     let s = as_plain_text(e.children());
                     trace!("paragraph text: {:?}", s);
                     if s.starts_with(": ") || s.contains("\n: ") {
-                        let (line, col) = linecol.get(loc.start);
-                        return Err(SiteError::DefinitionList(line, col));
+                        return Err(SiteError::DefinitionList(loc.line, loc.col));
                     }
                     stack.append_child(Content::Elt(e));
                 }
@@ -206,6 +207,7 @@ fn as_plain_text(content: &[Content]) -> String {
 
 #[derive(Debug, Clone)]
 pub struct Element {
+    loc: Option<Location>,
     tag: ElementTag,
     attrs: Vec<Attribute>,
     children: Vec<Content>,
@@ -214,12 +216,18 @@ pub struct Element {
 impl Element {
     pub fn new(tag: ElementTag) -> Self {
         Self {
+            loc: None,
             tag,
             attrs: vec![],
             children: vec![],
         }
     }
 
+    fn with_location(mut self, loc: Location) -> Self {
+        self.loc = Some(loc);
+        self
+    }
+
     fn push_attribute(&mut self, attr: Attribute) {
         self.attrs.push(attr);
     }
@@ -420,6 +428,18 @@ pub enum Content {
     Html(String),
 }
 
+#[derive(Debug, Clone, Copy)]
+struct Location {
+    line: usize,
+    col: usize,
+}
+
+impl Location {
+    fn new(line: usize, col: usize) -> Self {
+        Self { line, col }
+    }
+}
+
 struct Stack {
     stack: Vec<Element>,
 }
@@ -438,8 +458,8 @@ impl Stack {
         self.stack.push(e);
     }
 
-    fn push_tag(&mut self, tag: ElementTag) {
-        self.push(Element::new(tag));
+    fn push_tag(&mut self, tag: ElementTag, loc: Location) {
+        self.push(Element::new(tag).with_location(loc));
     }
 
     fn pop(&mut self) -> Element {
-- 
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