Merge pull request #1511 from joshrotenberg/example-semver

Use semver crate to validate version compatibility in nop-preprocessor example

Cargo.lock

@@ -1,5 +1,7 @@
 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
+version = 3
+
 [[package]]
 name = "aho-corasick"
 version = "0.7.18"
@@ -818,6 +820,7 @@ dependencies = [
  "pulldown-cmark",
  "regex",
  "select",
+ "semver",
  "serde",
  "serde_derive",
  "serde_json",
@@ -1360,6 +1363,24 @@ dependencies = [
  "markup5ever_rcdom",
 ]
 
+[[package]]
+name = "semver"
+version = "0.11.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f301af10236f6df4160f7c3f04eec6dbc70ace82d23326abad5edee88801c6b6"
+dependencies = [
+ "semver-parser",
+]
+
+[[package]]
+name = "semver-parser"
+version = "0.10.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "00b0bef5b7f9e0df16536d3961cfb6e84331c065b4066afb39768d0e319411f7"
+dependencies = [
+ "pest",
+]
+
 [[package]]
 name = "serde"
 version = "1.0.125"

Cargo.toml

@@ -49,6 +49,7 @@ ammonia = { version = "3", optional = true }
 
 [dev-dependencies]
 select = "0.5"
+semver = "0.11.0"
 pretty_assertions = "0.6"
 walkdir = "2.0"
 

examples/nop-preprocessor.rs

@@ -3,6 +3,7 @@ use clap::{App, Arg, ArgMatches, SubCommand};
 use mdbook::book::Book;
 use mdbook::errors::Error;
 use mdbook::preprocess::{CmdPreprocessor, Preprocessor, PreprocessorContext};
+use semver::{Version, VersionReq};
 use std::io;
 use std::process;
 
@@ -33,9 +34,10 @@ fn main() {
 fn handle_preprocessing(pre: &dyn Preprocessor) -> Result<(), Error> {
     let (ctx, book) = CmdPreprocessor::parse_input(io::stdin())?;
 
-    if ctx.mdbook_version != mdbook::MDBOOK_VERSION {
-        // We should probably use the `semver` crate to check compatibility
-        // here...
+    let book_version = Version::parse(&ctx.mdbook_version)?;
+    let version_req = VersionReq::parse(mdbook::MDBOOK_VERSION)?;
+
+    if version_req.matches(&book_version) != true {
         eprintln!(
             "Warning: The {} plugin was built against version {} of mdbook, \
              but we're being called from version {}",