feat! read document metadata from a YAML file

This is a huge change all in one commit, sorry. However, as it changes
a fundamental part of the command line interface (namely, what
constitutes as the input file), there doesn't seem a way to break this
into a tidy series of small commits.

Most of the diff is in subplot.md, where every scenario that invokes
Subplot needs multiple changes, thus touching much of the file.

The overall change is that where we previously had document metadata
in embedded YAML in the Markdown file, we now have it in a separate
YAML file. The Markdown file is named in the YAML file.

We still parse the Markdown with Pandoc for everything, except
codegen. Switching from Pandoc to pulldown_cmark for parsing will be
another big change that I didn't want to include in this huge change
set.

Sponsored-by: author

1 files changed, 17 insertions, 9 deletions

diff --git a/src/metadata.rs b/src/metadata.rs
index 5f5e183..dee0b50 100644
--- a/src/metadata.rs
+++ b/src/metadata.rs
@@ -1,11 +1,11 @@
-use crate::{Bindings, SubplotError, TemplateSpec};
+use crate::{Bindings, SubplotError, TemplateSpec, YamlMetadata};
 
 use std::collections::HashMap;
 use std::fmt::Debug;
 use std::ops::Deref;
 use std::path::{Path, PathBuf};
 
-use pandoc_ast::{Inline, Map, MetaValue, Pandoc};
+use pandoc_ast::{Inline, Map, MetaValue};
 
 use log::trace;
 
@@ -14,6 +14,7 @@ use log::trace;
 pub struct Metadata {
     title: String,
     date: Option<String>,
+    markdown_filename: PathBuf,
     bindings_filenames: Vec<PathBuf>,
     bindings: Bindings,
     impls: HashMap<String, DocumentImpl>,
@@ -32,22 +33,23 @@ impl Metadata {
     /// Construct a Metadata from a Document, if possible.
     pub fn new<P>(
         basedir: P,
-        doc: &Pandoc,
+        meta: &YamlMetadata,
         template: Option<&str>,
     ) -> Result<Metadata, SubplotError>
     where
         P: AsRef<Path> + Debug,
     {
-        let title = get_title(&doc.meta);
-        let date = get_date(&doc.meta);
-        let bindings_filenames = get_bindings_filenames(&doc.meta);
-        let bibliographies = get_bibliographies(basedir.as_ref(), &doc.meta);
-        let classes = get_classes(&doc.meta);
+        let map = meta.to_map();
+        let title = get_title(&map);
+        let date = get_date(&map);
+        let bindings_filenames = get_bindings_filenames(&map);
+        let bibliographies = get_bibliographies(basedir.as_ref(), &map);
+        let classes = get_classes(&map);
         trace!("Loaded basic metadata");
 
         let mut impls = HashMap::new();
 
-        if let Some(raw_impls) = doc.meta.get("impls") {
+        if let Some(raw_impls) = map.get("impls") {
             match raw_impls {
                 MetaValue::MetaMap(raw_impls) => {
                     for (impl_name, functions_filenames) in raw_impls.iter() {
@@ -74,6 +76,7 @@ impl Metadata {
         Ok(Metadata {
             title,
             date,
+            markdown_filename: meta.markdown().into(),
             bindings_filenames,
             bindings,
             impls,
@@ -92,6 +95,11 @@ impl Metadata {
         self.date.as_deref()
     }
 
+    /// Return filename of the markdown file.
+    pub fn markdown_filename(&self) -> &Path {
+        &self.markdown_filename
+    }
+
     /// Return filename where bindings are specified.
     pub fn bindings_filenames(&self) -> Vec<&Path> {
         self.bindings_filenames.iter().map(|f| f.as_ref()).collect()