implement laze_required_version

CHANGELOG.md

@@ -9,6 +9,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased] - ReleaseDate
 
+- add file-level `laze_required_version`
+
 ## [0.1.17] - 2023-10-06
 
 ### Fixed

Cargo.toml

@@ -41,6 +41,7 @@ clap_complete = "4.4.4"
 clap_mangen = "0.2.15"
 camino = { version = "1.1.6", features = ["serde1"] }
 evalexpr = "11.3.0"
+semver = { version = "1.0.20", features = ["serde"] }
 
 [profile.release]
 lto = "fat"

book/src/SUMMARY.md

@@ -18,6 +18,7 @@
 # Reference
 
 - [laze file format](./reference/laze_yaml.md)
+  - [laze_required_version](./reference/laze_required_version.md)
   - [apps](./reference/apps.md)
   - [builders](./reference/builders.md)
   - [contexts](./reference/contexts.md)

book/src/reference/laze_required_version.md

@@ -0,0 +1,10 @@
+# laze_required_version
+
+Expects a semver version string (`a.b.c`). Laze will refuse to read the file if
+its own version is smaller.
+
+Example:
+
+```yaml
+laze_required_version: 1.0.0
+```

src/data.rs

@@ -15,6 +15,7 @@ use std::time::Instant;
 
 use anyhow::{Context as _, Error, Result};
 use camino::{Utf8Path, Utf8PathBuf};
+use semver::Version;
 use serde::{Deserialize, Deserializer};
 
 use treestate::{FileState, TreeState};
@@ -40,6 +41,33 @@ where
     Deserialize::deserialize(deserializer).map(Some)
 }
 
+fn deserialize_version_checked<'de, D>(deserializer: D) -> Result<Option<Version>, D::Error>
+where
+    //    T: Deserialize<'de>,
+    D: Deserializer<'de>,
+{
+    use serde::de;
+
+    let version: Option<String> = Deserialize::deserialize(deserializer)?;
+    if let Some(version) = &version {
+        if let Ok(version) = Version::parse(version) {
+            let my_version = Version::parse(env!("CARGO_PKG_VERSION")).unwrap();
+            if version > my_version {
+                return Err(de::Error::custom(format!(
+                    "laze_required_version: got \"{version}\", expected any version <={my_version}"
+                )));
+            }
+            Ok(Some(version))
+        } else {
+            return Err(de::Error::custom(format!(
+                "error parsing \"{version}\" as semver version string"
+            )));
+        }
+    } else {
+        Ok(None)
+    }
+}
+
 #[derive(Debug, Serialize, Deserialize)]
 struct YamlFile {
     contexts: Option<Vec<YamlContext>>,
@@ -51,6 +79,8 @@ struct YamlFile {
     imports: Option<Vec<Import>>,
     subdirs: Option<Vec<String>>,
     defaults: Option<HashMap<String, YamlModule>>,
+    #[serde(default, deserialize_with = "deserialize_version_checked")]
+    laze_required_version: Option<Version>,
     #[serde(skip)]
     filename: Option<Utf8PathBuf>,
     #[serde(skip)]