Added support for validating Cow<'a, str> fields. (#56)

* Added support for validating Cow<'a, str> fields.

Keats/validator#55

* Corrected error message comparison in compiler-fail/length test.

Keats/validator#55

5 files changed, 22 insertions, 12 deletions

diff --git a/validator_derive/Cargo.toml b/validator_derive/Cargo.toml
index 3e80bbc..30c2d50 100644
--- a/validator_derive/Cargo.toml
+++ b/validator_derive/Cargo.toml
@@ -21,13 +21,13 @@ quote = "0.6"
 proc-macro2 = "0.4"
 if_chain = "0"
 validator = { version = "0.7", path = "../validator"}
+regex = "1"
+lazy_static = "1"
 
 [dev-dependencies]
 serde = "1.0"
 serde_derive = "1.0"
 serde_json = "1.0"
 compiletest_rs = "0.3"
-regex = "1"
-lazy_static = "1"
 
 
diff --git a/validator_derive/src/asserts.rs b/validator_derive/src/asserts.rs
index 53d76ae..cdd0028 100644
--- a/validator_derive/src/asserts.rs
+++ b/validator_derive/src/asserts.rs
@@ -1,3 +1,8 @@
+use regex::Regex;
+
+lazy_static! {
+    pub static ref COW_TYPE: Regex = Regex::new(r"Cow<'[a-z]+,str>").unwrap();
+}
 
 pub static NUMBER_TYPES: [&'static str; 36] = [
     "usize", "u8", "u16", "u32", "u64",
@@ -17,11 +22,12 @@ pub static NUMBER_TYPES: [&'static str; 36] = [
 pub fn assert_string_type(name: &str, field_type: &String) {
     if field_type != "String"
         && field_type != "&str"
+        && !COW_TYPE.is_match(field_type)
         && field_type != "Option<String>"
         && field_type != "Option<Option<String>>"
         && !(field_type.starts_with("Option<") && field_type.ends_with("str>"))
         && !(field_type.starts_with("Option<Option<") && field_type.ends_with("str>>")) {
-        panic!("`{}` validator can only be used on String, &str or an Option of those", name);
+        panic!("`{}` validator can only be used on String, &str, Cow<'_,str> or an Option of those", name);
     }
 }
 
@@ -45,9 +51,10 @@ pub fn assert_has_len(field_name: String, field_type: &String) {
         // a bit ugly
         && !(field_type.starts_with("Option<") && field_type.ends_with("str>"))
         && !(field_type.starts_with("Option<Option<") && field_type.ends_with("str>>"))
+        && !COW_TYPE.is_match(field_type)
         && field_type != "&str" {
             panic!(
-                "Validator `length` can only be used on types `String`, `&str` or `Vec` but found `{}` for field `{}`",
+                "Validator `length` can only be used on types `String`, `&str`, Cow<'_,str> or `Vec` but found `{}` for field `{}`",
                 field_type, field_name
             );
     }
diff --git a/validator_derive/src/lib.rs b/validator_derive/src/lib.rs
index a0a1c82..b5a76c1 100644
--- a/validator_derive/src/lib.rs
+++ b/validator_derive/src/lib.rs
@@ -1,20 +1,21 @@
 #![recursion_limit = "128"]
 
 #[macro_use]
-extern crate quote;
+extern crate if_chain;
+#[macro_use]
+extern crate lazy_static;
 extern crate proc_macro;
 extern crate proc_macro2;
 #[macro_use]
-extern crate syn;
+extern crate quote;
+extern crate regex;
 #[macro_use]
-extern crate if_chain;
+extern crate syn;
 extern crate validator;
 
-use std::collections::HashMap;
-
 use proc_macro::TokenStream;
 use quote::ToTokens;
-
+use std::collections::HashMap;
 use validator::Validator;
 
 
diff --git a/validator_derive/src/quoting.rs b/validator_derive/src/quoting.rs
index 272226e..20ca7a7 100644
--- a/validator_derive/src/quoting.rs
+++ b/validator_derive/src/quoting.rs
@@ -4,7 +4,7 @@ use proc_macro2::{self, Span};
 
 use lit::option_u64_to_tokens;
 use validation::{FieldValidation, SchemaValidation};
-use asserts::NUMBER_TYPES;
+use asserts::{COW_TYPE, NUMBER_TYPES};
 
 
 /// Pass around all the information needed for creating a validation
@@ -31,6 +31,8 @@ impl FieldQuoter {
 
         if self._type.starts_with("Option<") {
             quote!(#ident)
+        } else if COW_TYPE.is_match(&self._type.as_ref()) {
+            quote!(self.#ident.as_ref())
         } else if self._type.starts_with("&") || NUMBER_TYPES.contains(&self._type.as_ref()) {
             quote!(self.#ident)
         } else {
diff --git a/validator_derive/tests/compile-fail/length/wrong_type.rs b/validator_derive/tests/compile-fail/length/wrong_type.rs
index a9d53d4..3dd1fb0 100644
--- a/validator_derive/tests/compile-fail/length/wrong_type.rs
+++ b/validator_derive/tests/compile-fail/length/wrong_type.rs
@@ -4,7 +4,7 @@ use validator::Validate;
 
 #[derive(Validate)]
 //~^ ERROR: proc-macro derive panicked
-//~^^ HELP: Validator `length` can only be used on types `String`, `&str` or `Vec` but found `usize`
+//~^^ HELP: Validator `length` can only be used on types `String`, `&str`, Cow<'_,str> or `Vec` but found `usize`
 struct Test {
     #[validate(length())]
     s: usize,