README: update with MSRV, and update mechanism for doing so.

Thanks to @kaesluder and @bioinformatist for various improvements that
are working together here!

Cargo.toml

@@ -50,6 +50,7 @@ in-place = { version = "0.2.0", optional = true }
 
 [dev-dependencies]
 ntest = "0.9"
+toml = "0.8"
 
 [target.'cfg(not(target_arch="wasm32"))'.dev-dependencies]
 propfuzz = "0.0.1"

README.md

@@ -24,7 +24,7 @@ Specify it as a requirement in `Cargo.toml`:
 comrak = "0.22"
 ```
 
-Comrak supports Rust stable.
+Comrak's library supports Rust <span class="msrv">1.62.1</span>+.
 
 ### Mac & Linux Binaries
 
@@ -56,6 +56,9 @@ Options:
           
           [default: /Users/kivikakk/.config/comrak/config]
 
+  -i, --inplace
+          To perform an in-place formatting
+
       --hardbreaks
           Treat newlines as hard line breaks
 

examples/update-readme.rs

@@ -1,64 +1,77 @@
 // Update the "comrak --help" text in Comrak's own README.
 
+use in_place::InPlace;
+use std::error::Error;
 use std::fmt::Write;
 use std::str;
+use toml::Table;
 
-use comrak::nodes::{AstNode, NodeValue};
+use comrak::nodes::NodeValue;
 use comrak::{format_commonmark, parse_document, Arena, Options};
 
 const DEPENDENCIES: &str = "[dependencies]\ncomrak = ";
 const HELP: &str = "$ comrak --help\n";
 
-fn main() -> Result<(), Box<dyn std::error::Error + 'static>> {
+fn main() -> Result<(), Box<dyn Error>> {
     let arena = Arena::new();
 
-    let readme = std::fs::read_to_string("README.md")?;
+    let inp = InPlace::new("README.md").open()?;
+    let readme = std::io::read_to_string(inp.reader())?;
     let doc = parse_document(&arena, &readme, &Options::default());
 
-    fn iter_nodes<'a, F>(node: &'a AstNode<'a>, f: &F)
-    where
-        F: Fn(&'a AstNode<'a>),
-    {
-        f(node);
-        for c in node.children() {
-            iter_nodes(c, f);
-        }
-    }
+    let cargo_toml = std::fs::read_to_string("Cargo.toml")?.parse::<Table>()?;
+    let msrv = cargo_toml["package"].as_table().unwrap()["rust-version"]
+        .as_str()
+        .unwrap();
 
-    iter_nodes(doc, &|node| {
-        if let NodeValue::CodeBlock(ref mut ncb) = node.data.borrow_mut().value {
-            // Look for the Cargo.toml example block.
-            if ncb.info == "toml" && ncb.literal.starts_with(DEPENDENCIES) {
-                let mut content = DEPENDENCIES.to_string();
-                let mut version_parts = comrak::version().split('.').collect::<Vec<&str>>();
-                version_parts.pop();
-                write!(content, "\"{}\"", version_parts.join(".")).unwrap();
-                ncb.literal = content;
-            }
+    let mut in_msrv = false;
+    for node in doc.descendants() {
+        match node.data.borrow_mut().value {
+            NodeValue::CodeBlock(ref mut ncb) => {
+                // Look for the Cargo.toml example block.
+                if ncb.info == "toml" && ncb.literal.starts_with(DEPENDENCIES) {
+                    let mut content = DEPENDENCIES.to_string();
+                    let mut version_parts = comrak::version().split('.').collect::<Vec<&str>>();
+                    version_parts.pop();
+                    write!(content, "\"{}\"", version_parts.join(".")).unwrap();
+                    ncb.literal = content;
+                }
 
-            // Look for a console code block whose contents starts with the HELP string.
-            // Replace its contents with the same string and the actual command output.
-            if ncb.info == "console" && ncb.literal.starts_with(HELP) {
-                let mut content = HELP.to_string();
-                let mut cmd = std::process::Command::new("cargo");
-                content.push_str(
-                    str::from_utf8(
-                        &cmd.args(["run", "--all-features", "--", "--help"])
-                            .output()
-                            .unwrap()
-                            .stdout,
-                    )
-                    .unwrap(),
-                );
-                ncb.literal = content;
+                // Look for a console code block whose contents starts with the HELP string.
+                // Replace its contents with the same string and the actual command output.
+                if ncb.info == "console" && ncb.literal.starts_with(HELP) {
+                    let mut content = HELP.to_string();
+                    let mut cmd = std::process::Command::new("cargo");
+                    content.push_str(
+                        str::from_utf8(
+                            &cmd.args(["run", "--all-features", "--", "--help"])
+                                .output()
+                                .unwrap()
+                                .stdout,
+                        )
+                        .unwrap(),
+                    );
+                    ncb.literal = content;
+                }
+            }
+            NodeValue::HtmlInline(ref mut s) => {
+                if s == "<span class=\"msrv\">" {
+                    in_msrv = true;
+                } else if in_msrv && s == "</span>" {
+                    in_msrv = false;
+                }
             }
+            NodeValue::Text(ref mut t) => {
+                if in_msrv {
+                    std::mem::swap(t, &mut msrv.to_string());
+                }
+            }
+            _ => {}
         }
-    });
-
-    let mut out = vec![];
-    format_commonmark(doc, &Options::default(), &mut out).unwrap();
+    }
 
-    std::fs::write("README.md", &out)?;
+    format_commonmark(doc, &Options::default(), &mut inp.writer())?;
+    inp.save()?;
 
     Ok(())
 }