From 54f5e9fd883e207931baa9c87b6181ca724d6bab Mon Sep 17 00:00:00 2001
From: Ben Bridle <bridle.benjamin@gmail.com>
Date: Thu, 25 Aug 2022 21:09:25 +1200
Subject: Initial commit

---
 src/parse_heirarchical.rs | 137 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 137 insertions(+)
 create mode 100644 src/parse_heirarchical.rs

(limited to 'src/parse_heirarchical.rs')

diff --git a/src/parse_heirarchical.rs b/src/parse_heirarchical.rs
new file mode 100644
index 0000000..75c2bec
--- /dev/null
+++ b/src/parse_heirarchical.rs
@@ -0,0 +1,137 @@
+use crate::*;
+
+macro_rules! get_subsection {
+    ($t:ident) => {
+        pub fn get_subsection(&self, name: &str) -> Option<&$t> {
+            for section in &self.sections {
+                if line_to_string(&section.title) == name {
+                    return Some(section);
+                }
+            }
+            return None;
+        }
+    };
+}
+
+#[derive(Default)]
+pub struct Document {
+    pub preamble: Vec<Block>,
+    pub sections: Vec<TopLevelSection>,
+}
+impl Document {
+    get_subsection! {TopLevelSection}
+}
+
+#[derive(Default)]
+pub struct TopLevelSection {
+    pub title: Line,
+    pub content: Vec<Block>,
+    pub sections: Vec<MidLevelSection>,
+}
+impl TopLevelSection {
+    get_subsection! {MidLevelSection}
+}
+
+#[derive(Default)]
+pub struct MidLevelSection {
+    pub title: Line,
+    pub content: Vec<Block>,
+    pub sections: Vec<LowLevelSection>,
+}
+impl MidLevelSection {
+    get_subsection! {LowLevelSection}
+}
+
+#[derive(Default)]
+pub struct LowLevelSection {
+    pub title: Line,
+    pub content: Vec<Block>,
+}
+
+pub fn parse_heirarchical(markdown: &str) -> Result<Document, ()> {
+    macro_rules! push_section {
+        ($from:ident => $to:ident) => {
+            $to.sections.push(std::mem::take(&mut $from))
+        };
+    }
+    let mut document = Document::default();
+    let mut h1_buffer = TopLevelSection::default();
+    let mut h2_buffer = MidLevelSection::default();
+    let mut h3_buffer = LowLevelSection::default();
+    let mut level = 0;
+
+    let blocks = parse(markdown);
+    for block in blocks {
+        match (level, block) {
+            (0, Block::Heading1(title)) => {
+                h1_buffer.title = title;
+                level = 1;
+            }
+            (0, Block::Heading2(_)) => return Err(()),
+            (0, Block::Heading3(_)) => return Err(()),
+            (0, block) => document.preamble.push(block),
+            (1, Block::Heading1(title)) => {
+                push_section!(h1_buffer => document);
+                h1_buffer.title = title;
+            }
+            (1, Block::Heading2(title)) => {
+                h2_buffer.title = title;
+                level = 2;
+            }
+            (1, Block::Heading3(_)) => return Err(()),
+            (1, block) => h1_buffer.content.push(block),
+            (2, Block::Heading1(title)) => {
+                push_section!(h2_buffer => h1_buffer);
+                push_section!(h1_buffer => document);
+                h1_buffer.title = title;
+                level = 1;
+            }
+            (2, Block::Heading2(title)) => {
+                push_section!(h2_buffer => h1_buffer);
+                h2_buffer.title = title;
+            }
+            (2, Block::Heading3(title)) => {
+                h3_buffer.title = title;
+                level = 3;
+            }
+            (2, block) => h2_buffer.content.push(block),
+            (3, Block::Heading1(title)) => {
+                push_section!(h3_buffer => h2_buffer);
+                push_section!(h2_buffer => h1_buffer);
+                push_section!(h1_buffer => document);
+                h1_buffer.title = title;
+                level = 1;
+            }
+            (3, Block::Heading2(title)) => {
+                push_section!(h3_buffer => h2_buffer);
+                push_section!(h2_buffer => h1_buffer);
+                h2_buffer.title = title;
+                level = 2;
+            }
+            (3, Block::Heading3(title)) => {
+                push_section!(h3_buffer => h2_buffer);
+                h3_buffer.title = title;
+            }
+            (3, block) => h3_buffer.content.push(block),
+            _ => unreachable!(),
+        }
+    }
+
+    // Push all in-progress sections
+    match level {
+        3 => {
+            push_section!(h3_buffer => h2_buffer);
+            push_section!(h2_buffer => h1_buffer);
+            push_section!(h1_buffer => document);
+        }
+        2 => {
+            push_section!(h2_buffer => h1_buffer);
+            push_section!(h1_buffer => document);
+        }
+        1 => {
+            push_section!(h1_buffer => document);
+        }
+        _ => (),
+    }
+    Ok(document)
+}
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