twelf: Make shellexpand dependency optional (#40)

We don't need this functionality for our use case and the transitive dependency[0]
of the MPL licensed `option-ext` crate is undesired.

[0]: `option-ext <- dirs-sys <- dirs <- shellexpand <- twelf`

config-derive/Cargo.toml

@@ -35,3 +35,4 @@
     yaml  = []
     default_trait = []
     custom_fn = []
+    shellexpand = []

config-derive/src/lib.rs

@@ -282,11 +282,28 @@ fn build_env_branch(opt_struct_name: &Ident, struct_gen: &Generics) -> proc_macr
     },}
 }
 
+#[cfg(any(
+    feature = "json",
+    feature = "yaml",
+    feature = "toml",
+    feature = "ini",
+    feature = "dhall"
+))]
+fn build_shellexpand() -> proc_macro2::TokenStream {
+    #[cfg(feature = "shellexpand")]
+    quote! { let content = ::twelf::reexports::shellexpand::env(&file_content)? }
+
+    #[cfg(not(feature = "shellexpand"))]
+    quote! { let content = file_content }
+}
+
 fn build_json_branch() -> proc_macro2::TokenStream {
+    #[cfg(feature = "json")]
+    let shellexpand = build_shellexpand();
     #[cfg(feature = "json")]
     let json_branch = quote! { ::twelf::Layer::Json(filepath) => {
         let file_content = std::fs::read_to_string(filepath)?;
-        let content = ::twelf::reexports::shellexpand::env(&file_content)?;
+        #shellexpand;
         (::twelf::reexports::serde_json::from_str(&content)?,None)
     }, };
     #[cfg(not(feature = "json"))]
@@ -295,13 +312,15 @@ fn build_json_branch() -> proc_macro2::TokenStream {
 }
 
 fn build_toml_branch() -> proc_macro2::TokenStream {
+    #[cfg(feature = "toml")]
+    let shellexpand = build_shellexpand();
     #[cfg(feature = "toml")]
     let toml_branch = quote! { ::twelf::Layer::Toml(filepath) => {
         let file_content = std::fs::read_to_string(filepath)?;
         // Strip out comments (lines starting with #)
         let file_content = file_content.lines().filter(|line| !line.trim().starts_with("#")).collect::<Vec<_>>().join("\n");
 
-        let content = ::twelf::reexports::shellexpand::env(&file_content)?;
+        #shellexpand;
         (::twelf::reexports::toml::from_str(&content)?,None)
     }, };
     #[cfg(not(feature = "toml"))]
@@ -310,12 +329,14 @@ fn build_toml_branch() -> proc_macro2::TokenStream {
 }
 
 fn build_yaml_branch() -> proc_macro2::TokenStream {
+    #[cfg(feature = "yaml")]
+    let shellexpand = build_shellexpand();
     #[cfg(feature = "yaml")]
     let yaml_branch = quote! { ::twelf::Layer::Yaml(filepath) => {
         let file_content = std::fs::read_to_string(filepath)?;
         // Strip out comments (lines starting with #)
         let file_content = file_content.lines().filter(|line| !line.trim().starts_with("#")).collect::<Vec<_>>().join("\n");
-        let content = ::twelf::reexports::shellexpand::env(&file_content)?;
+        #shellexpand;
         (::twelf::reexports::serde_yaml::from_str(&content)?,None)
     }, };
     #[cfg(not(feature = "yaml"))]
@@ -324,13 +345,15 @@ fn build_yaml_branch() -> proc_macro2::TokenStream {
 }
 
 fn build_dhall_branch() -> proc_macro2::TokenStream {
+    #[cfg(feature = "dhall")]
+    let shellexpand = build_shellexpand();
     #[cfg(feature = "dhall")]
     let dhall_branch = quote! { ::twelf::Layer::Dhall(filepath) => {
         let file_content = std::fs::read_to_string(filepath)?;
         // Strip out comments (lines starting with --)
         let file_content = file_content.lines().filter(|line| !line.trim().starts_with("--")).collect::<Vec<_>>().join("\n");
 
-        let content = ::twelf::reexports::shellexpand::env(&file_content)?;
+        #shellexpand;
         (::twelf::reexports::serde_dhall::from_str(&content).parse()?,None)
     }, };
     #[cfg(not(feature = "dhall"))]
@@ -340,11 +363,12 @@ fn build_dhall_branch() -> proc_macro2::TokenStream {
 
 #[cfg(feature = "ini")]
 fn build_ini_branch(opt_struct_name: &Ident, struct_gen: &Generics) -> proc_macro2::TokenStream {
+    let shellexpand = build_shellexpand();
     quote! { ::twelf::Layer::Ini(filepath) => {
         let file_content = std::fs::read_to_string(filepath)?;
         // Strip out comments (lines starting with ;)
         let file_content = file_content.lines().filter(|line| !line.trim().starts_with(";")).collect::<Vec<_>>().join("\n");
-        let content = ::twelf::reexports::shellexpand::env(&file_content)?;
+        #shellexpand;
        let tmp_cfg: #opt_struct_name #struct_gen = ::twelf::reexports::serde_ini::from_str(&content)?;
        (::twelf::reexports::serde_json::to_value(tmp_cfg)?,None)
     }, }

twelf/Cargo.toml

@@ -27,13 +27,14 @@
     shellexpand = { version = "3.1.0", optional = true }
 
 [features]
-    clap    = ["clap_rs", "config-derive/clap", "envy"]
-    default = ["env", "clap"]
-    dhall   = ["serde_dhall", "config-derive/dhall", "shellexpand"]
-    env     = ["envy", "config-derive/env"]
-    ini     = ["serde_ini", "config-derive/ini", "shellexpand"]
-    json    = ["config-derive/json", "shellexpand"]
-    toml    = ["toml_rs", "config-derive/toml", "shellexpand"]
-    yaml    = ["serde_yaml", "config-derive/yaml", "shellexpand"]
+    clap          = ["clap_rs", "config-derive/clap", "envy"]
+    default       = ["env", "clap", "shellexpand"]
+    shellexpand   = ["dep:shellexpand", "config-derive/shellexpand"]
+    dhall         = ["serde_dhall", "config-derive/dhall"]
+    env           = ["envy", "config-derive/env"]
+    ini           = ["serde_ini", "config-derive/ini"]
+    json          = ["config-derive/json"]
+    toml          = ["toml_rs", "config-derive/toml"]
+    yaml          = ["serde_yaml", "config-derive/yaml"]
     default_trait = ["config-derive/default_trait"]
-    custom_fn = ["dyn-clone", "config-derive/custom_fn", "shellexpand"]
+    custom_fn     = ["dyn-clone", "config-derive/custom_fn"]

twelf/src/error.rs

@@ -1,16 +1,29 @@
+#[cfg(all(
+    any(
+        feature = "json",
+        feature = "yaml",
+        feature = "toml",
+        feature = "ini",
+        feature = "dhall"
+    ),
+    feature = "shellexpand"
+))]
 use std::env::VarError;
 
 use thiserror::Error as ErrorTrait;
 
 /// Error generated when instantiate configuration
 #[derive(Debug, ErrorTrait)]
 pub enum Error {
-    #[cfg(any(
-        feature = "json",
-        feature = "yaml",
-        feature = "toml",
-        feature = "ini",
-        feature = "dhall"
+    #[cfg(all(
+        any(
+            feature = "json",
+            feature = "yaml",
+            feature = "toml",
+            feature = "ini",
+            feature = "dhall"
+        ),
+        feature = "shellexpand"
     ))]
     #[error("env lookup error")]
     ShellExpand(#[from] shellexpand::LookupError<VarError>),

twelf/src/lib.rs

@@ -16,12 +16,15 @@ pub mod reexports {
     pub use log;
     pub use serde;
     pub use serde_json;
-    #[cfg(any(
-        feature = "json",
-        feature = "yaml",
-        feature = "toml",
-        feature = "ini",
-        feature = "dhall"
+    #[cfg(all(
+        any(
+            feature = "json",
+            feature = "yaml",
+            feature = "toml",
+            feature = "ini",
+            feature = "dhall"
+        ),
+        feature = "shellexpand"
     ))]
     pub use shellexpand;