1 files changed, 128 insertions, 4 deletions

diff --git a/src/parser/conversion.rs b/src/parser/conversion.rs
index ad214d5..50a7fb2 100644
--- a/src/parser/conversion.rs
+++ b/src/parser/conversion.rs
@@ -7,14 +7,138 @@ use pest::iterators::Pairs;
 use crate::document_tree::{
     HasChildren,
     elements as e,
+    element_categories as c,
 };
 
 use super::pest_rst::Rule;
 
 
+fn ssubel_to_section_unchecked_mut(ssubel: &mut c::StructuralSubElement) -> &mut e::Section {
+    match ssubel {
+        c::StructuralSubElement::SubStructure(ref mut b) => match **b {
+            c::SubStructure::Section(ref mut s) => s,
+            _ => unreachable!(),
+        },
+        _ => unreachable!(),
+    }
+}
+
+
+fn get_level<'tl>(toplevel: &'tl mut Vec<c::StructuralSubElement>, section_idxs: &[Option<usize>]) -> &'tl mut Vec<c::StructuralSubElement> {
+    let mut level = toplevel;
+    for maybe_i in section_idxs {
+        if let Some(i) = *maybe_i {
+            level = ssubel_to_section_unchecked_mut(&mut level[i]).children_mut();
+        }
+    }
+    level
+}
+
+
 pub fn convert_document(pairs: Pairs<Rule>) -> Result<e::Document, Error> {
-    let structural_elems = pairs.map(block::convert_ssubel)
-        .filter_map(|elem| match elem { Ok(Some(e)) => Some(Ok(e)), Err(e) => Some(Err(e)), Ok(None) => None })
-        .collect::<Result<_,_>>()?;
-    Ok(e::Document::with_children(structural_elems))
+    use self::block::TitleOrSsubel::*;
+    
+    let mut toplevel: Vec<c::StructuralSubElement> = vec![];
+    // The kinds of section titles encountered.
+    // `section_idx[x]` has the kind `kinds[x]`, but `kinds` can be longer
+    let mut kinds: Vec<block::TitleKind> = vec![];
+    // Recursive indices into the tree, pointing at the active sections.
+    // `None`s indicate skipped section levels:
+    // toplevel[section_idxs.flatten()[0]].children[section_idxs.flatten()[1]]...
+    let mut section_idxs: Vec<Option<usize>> = vec![];
+    
+    for pair in pairs {
+        if let Some(ssubel) = block::convert_ssubel(pair)? { match ssubel {
+            Title(title, kind) => {
+                match kinds.iter().position(|k| k == &kind) {
+                    // Idx points to the level we want to add,
+                    // so idx-1 needs to be the last valid index.
+                    Some(idx) => {
+                        // If idx < len: Remove found section and all below
+                        section_idxs.truncate(idx);
+                        // If idx > len: Add None for skipped levels
+                        // TODO: test skipped levels
+                        while section_idxs.len() < idx { section_idxs.push(None) }
+                    },
+                    None => kinds.push(kind),
+                }
+                let super_level = get_level(&mut toplevel, &section_idxs);
+                super_level.push(e::Section::with_children(vec![title.into()]).into());
+                section_idxs.push(Some(super_level.len() - 1));
+            },
+            Ssubel(elem) => get_level(&mut toplevel, &section_idxs).push(elem),
+        }}
+    }
+    Ok(e::Document::with_children(toplevel))
+}
+
+
+#[cfg(test)]
+mod tests {
+    use crate::{
+        parser::parse,
+        document_tree::{
+            elements as e,
+            element_categories as c,
+            HasChildren,
+        }
+    };
+    
+    fn ssubel_to_section(ssubel: &c::StructuralSubElement) -> &e::Section {
+        match ssubel {
+            c::StructuralSubElement::SubStructure(ref b) => match **b {
+                c::SubStructure::Section(ref s) => s,
+                ref c => panic!("Expected section, not {:?}", c),
+            },
+            ref c => panic!("Expected SubStructure, not {:?}", c),
+        }
+    }
+    
+    const SECTIONS: &str = "\
+Intro before first section title
+
+Level 1
+*******
+
+-------
+Level 2
+-------
+
+Level 3
+=======
+
+L1 again
+********
+
+L3 again, skipping L2
+=====================
+";
+    
+    #[test]
+    fn convert_skipped_section() {
+        let doctree = parse(SECTIONS).unwrap();
+        let lvl0 = doctree.children();
+        assert_eq!(lvl0.len(), 3, "Should be a paragraph and 2 sections: {:?}", lvl0);
+        
+        assert_eq!(lvl0[0], e::Paragraph::with_children(vec![
+            "Intro before first section title".to_owned().into()
+        ]).into(), "The intro text should fit");
+        
+        let lvl1a = ssubel_to_section(&lvl0[1]).children();
+        assert_eq!(lvl1a.len(), 2, "The 1st lvl1 section should have (a title and) a single lvl2 section as child: {:?}", lvl1a);
+        //TODO: test title lvl1a[0]
+        let lvl2  = ssubel_to_section(&lvl1a[1]).children();
+        assert_eq!(lvl2.len(), 2, "The lvl2 section should have (a title and) a single lvl3 section as child: {:?}", lvl2);
+        //TODO: test title lvl2[0]
+        let lvl3a = ssubel_to_section(&lvl2[1]).children();
+        assert_eq!(lvl3a.len(), 1, "The 1st lvl3 section should just a title: {:?}", lvl3a);
+        //TODO: test title lvl3a[0]
+        
+        let lvl1b = ssubel_to_section(&lvl0[2]).children();
+        assert_eq!(lvl1b.len(), 2, "The 2nd lvl1 section should have (a title and) a single lvl2 section as child: {:?}", lvl1b);
+        //TODO: test title lvl1b[0]
+        let lvl3b = ssubel_to_section(&lvl1b[1]).children();
+        assert_eq!(lvl3b.len(), 1, "The 2nd lvl3 section should have just a title: {:?}", lvl3b);
+        //TODO: test title lvl3b[0]
+    }
 }