Improve md5 and sha256 code (#3841)

* Refactor Hash code to simplify md5 and sha256 implementations

Md5 and Sha256 (and other future digests) require less boilerplate code
now. Error reporting includues the name of the hash again.

* Add missing hash sha256 test

crates/nu-command/src/commands/generators/hash_/generic_digest.rs

@@ -1,14 +1,57 @@
+use std::marker::PhantomData;
+
 use crate::prelude::*;
 use nu_errors::ShellError;
-use nu_protocol::ShellTypeName;
-use nu_protocol::{ColumnPath, Primitive, UntaggedValue, Value};
+use nu_protocol::{ColumnPath, Primitive, SyntaxShape, UntaggedValue, Value};
+use nu_protocol::{ShellTypeName, Signature};
 use nu_source::Tag;
 
-pub fn run<D>(args: CommandArgs) -> Result<OutputStream, ShellError>
+pub trait HashDigest: digest::Digest {
+    fn name() -> &'static str;
+    fn examples() -> Vec<Example>;
+}
+
+pub struct SubCommand<D: HashDigest> {
+    name_string: String,
+    usage_string: String,
+    phantom: PhantomData<D>,
+}
+
+impl<D: HashDigest> Default for SubCommand<D> {
+    fn default() -> Self {
+        Self {
+            name_string: format!("hash {}", D::name()),
+            usage_string: format!("{} encode a value", D::name()),
+            phantom: PhantomData,
+        }
+    }
+}
+
+impl<D> WholeStreamCommand for SubCommand<D>
 where
-    D: digest::Digest,
+    D: HashDigest + Send + Sync,
     digest::Output<D>: core::fmt::LowerHex,
 {
+    fn name(&self) -> &str {
+        &self.name_string
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build(self.name()).rest(
+            SyntaxShape::ColumnPath,
+            format!("optionally {} encode data by column paths", D::name()),
+        )
+    }
+
+    fn usage(&self) -> &str {
+        &self.usage_string
+    }
+
+    fn examples(&self) -> Vec<Example> {
+        D::examples()
+    }
+
+    fn run(&self, args: CommandArgs) -> Result<OutputStream, ShellError> {
         let column_paths: Vec<ColumnPath> = args.rest(0)?;
 
         Ok(args
@@ -30,11 +73,12 @@ where
                 }
             })
             .into_input_stream())
+    }
 }
 
 pub fn action<D>(input: &Value, tag: Tag) -> Result<Value, ShellError>
 where
-    D: digest::Digest,
+    D: HashDigest,
     digest::Output<D>: core::fmt::LowerHex,
 {
     match &input.value {
@@ -49,7 +93,7 @@ where
         other => {
             let got = format!("got {}", other.type_name());
             Err(ShellError::labeled_error(
-                "value is not supported for hashing",
+                format!("value is not supported for hashing as {}", D::name()),
                 got,
                 tag.span,
             ))

crates/nu-command/src/commands/generators/hash_/md5_.rs

@@ -1,34 +1,17 @@
 use crate::prelude::*;
 use md5::Md5;
-use nu_engine::WholeStreamCommand;
-use nu_errors::ShellError;
-use nu_protocol::{Signature, SyntaxShape, UntaggedValue};
+use nu_protocol::UntaggedValue;
 
-use super::generic_digest;
+use super::generic_digest::{self, HashDigest};
 
-pub struct SubCommand;
+pub type SubCommand = generic_digest::SubCommand<Md5>;
 
-impl WholeStreamCommand for SubCommand {
-    fn name(&self) -> &str {
-        "hash md5"
+impl HashDigest for Md5 {
+    fn name() -> &'static str {
+        "md5"
     }
 
-    fn signature(&self) -> Signature {
-        Signature::build("hash md5").rest(
-            SyntaxShape::ColumnPath,
-            "optionally md5 encode data by column paths",
-        )
-    }
-
-    fn usage(&self) -> &str {
-        "md5 encode a value"
-    }
-
-    fn run(&self, args: CommandArgs) -> Result<OutputStream, ShellError> {
-        generic_digest::run::<Md5>(args)
-    }
-
-    fn examples(&self) -> Vec<Example> {
+    fn examples() -> Vec<Example> {
         vec![
             Example {
                 description: "md5 encode a string",

crates/nu-command/src/commands/generators/hash_/sha256_.rs

@@ -1,34 +1,17 @@
 use crate::prelude::*;
-use nu_engine::WholeStreamCommand;
-use nu_errors::ShellError;
-use nu_protocol::{Signature, SyntaxShape, UntaggedValue};
+use nu_protocol::UntaggedValue;
 use sha2::Sha256;
 
-use super::generic_digest;
+use super::generic_digest::{self, HashDigest};
 
-pub struct SubCommand;
+pub type SubCommand = generic_digest::SubCommand<Sha256>;
 
-impl WholeStreamCommand for SubCommand {
-    fn name(&self) -> &str {
-        "hash sha256"
+impl HashDigest for Sha256 {
+    fn name() -> &'static str {
+        "sha256"
     }
 
-    fn signature(&self) -> Signature {
-        Signature::build("hash sha256").rest(
-            SyntaxShape::ColumnPath,
-            "optionally sha256 encode data by column paths",
-        )
-    }
-
-    fn usage(&self) -> &str {
-        "sha256 encode a value"
-    }
-
-    fn run(&self, args: CommandArgs) -> Result<OutputStream, ShellError> {
-        generic_digest::run::<Sha256>(args)
-    }
-
-    fn examples(&self) -> Vec<Example> {
+    fn examples() -> Vec<Example> {
         vec![
             Example {
                 description: "sha256 encode a string",

crates/nu-command/src/default_context.rs

@@ -84,8 +84,8 @@ pub fn create_default_context(interactive: bool) -> Result<EvaluationContext, Bo
             // Text manipulation
             whole_stream_command(Hash),
             whole_stream_command(HashBase64),
-            whole_stream_command(HashMd5),
-            whole_stream_command(HashSha256),
+            whole_stream_command(HashMd5::default()),
+            whole_stream_command(HashSha256::default()),
             whole_stream_command(Split),
             whole_stream_command(SplitColumn),
             whole_stream_command(SplitRow),

crates/nu-command/tests/commands/hash_/mod.rs

@@ -96,3 +96,19 @@ fn md5_works_with_file() {
 
     assert_eq!(actual.out, "4de97601d232c427977ef11db396c951");
 }
+
+#[test]
+fn sha256_works_with_file() {
+    let actual = nu!(
+        cwd: "tests/fixtures/formats", pipeline(
+        r#"
+        open sample.db | hash sha256
+        "#
+        )
+    );
+
+    assert_eq!(
+        actual.out,
+        "2f5050e7eea415c1f3d80b5d93355efd15043ec9157a2bb167a9e73f2ae651f2"
+    );
+}