Begin migration away from arg serialization (#3281)

* initial implementation

* Move a few commands over to new arg system

* Fix char also

crates/nu-engine/src/command_args.rs

@@ -3,6 +3,7 @@ use crate::env::host::Host;
 use crate::evaluate::scope::Scope;
 use crate::evaluation_context::EvaluationContext;
 use crate::shell::shell_manager::ShellManager;
+use crate::FromValue;
 use crate::{call_info::UnevaluatedCallInfo, config_holder::ConfigHolder};
 use derive_new::new;
 use getset::Getters;
@@ -171,11 +172,44 @@ impl EvaluatedCommandArgs {
             .ok_or_else(|| ShellError::unimplemented("Better error: expect_nth"))
     }
 
-    pub fn get(&self, name: &str) -> Option<&Value> {
-        self.call_info.args.get(name)
+    pub fn get_flag<T: FromValue>(&self, name: &str) -> Option<Result<T, ShellError>> {
+        self.call_info
+            .args
+            .get(name)
+            .map(|x| FromValue::from_value(x))
     }
 
-    pub fn has(&self, name: &str) -> bool {
+    pub fn has_flag(&self, name: &str) -> bool {
         self.call_info.args.has(name)
     }
+
+    pub fn req<T: FromValue>(&self, pos: usize) -> Result<T, ShellError> {
+        if let Some(v) = self.nth(pos) {
+            FromValue::from_value(v)
+        } else {
+            Err(ShellError::labeled_error(
+                "Position beyond end of command arguments",
+                "can't access beyond end of command arguments",
+                self.call_info.name_tag.span,
+            ))
+        }
+    }
+
+    pub fn opt<T: FromValue>(&self, pos: usize) -> Option<Result<T, ShellError>> {
+        if let Some(v) = self.nth(pos) {
+            Some(FromValue::from_value(v))
+        } else {
+            None
+        }
+    }
+
+    pub fn rest<T: FromValue>(&self, starting_pos: usize) -> Result<Vec<T>, ShellError> {
+        let mut output = vec![];
+
+        for val in self.call_info.args.positional_iter().skip(starting_pos) {
+            output.push(FromValue::from_value(val)?);
+        }
+
+        Ok(output)
+    }
 }

crates/nu-engine/src/from_value.rs

@@ -0,0 +1,281 @@
+use std::path::PathBuf;
+
+use chrono::{DateTime, FixedOffset};
+use nu_errors::ShellError;
+use nu_protocol::{
+    hir::CapturedBlock, ColumnPath, Dictionary, Primitive, Range, UntaggedValue, Value,
+};
+use nu_source::{Tagged, TaggedItem};
+
+pub trait FromValue: Sized {
+    fn from_value(v: &Value) -> Result<Self, ShellError>;
+}
+
+impl FromValue for Value {
+    fn from_value(v: &Value) -> Result<Self, ShellError> {
+        Ok(v.clone())
+    }
+}
+
+impl FromValue for num_bigint::BigInt {
+    fn from_value(v: &Value) -> Result<Self, ShellError> {
+        match v {
+            Value {
+                value: UntaggedValue::Primitive(Primitive::Int(i)),
+                ..
+            }
+            | Value {
+                value: UntaggedValue::Primitive(Primitive::Filesize(i)),
+                ..
+            }
+            | Value {
+                value: UntaggedValue::Primitive(Primitive::Duration(i)),
+                ..
+            } => Ok(i.clone()),
+            Value { tag, .. } => Err(ShellError::labeled_error(
+                "Can't convert to integer",
+                "can't convert to integer",
+                tag.span,
+            )),
+        }
+    }
+}
+
+impl FromValue for u64 {
+    fn from_value(v: &Value) -> Result<Self, ShellError> {
+        v.as_u64()
+    }
+}
+
+impl FromValue for usize {
+    fn from_value(v: &Value) -> Result<Self, ShellError> {
+        v.as_usize()
+    }
+}
+
+impl FromValue for i64 {
+    fn from_value(v: &Value) -> Result<Self, ShellError> {
+        v.as_i64()
+    }
+}
+
+impl FromValue for i32 {
+    fn from_value(v: &Value) -> Result<Self, ShellError> {
+        v.as_i32()
+    }
+}
+
+impl FromValue for bigdecimal::BigDecimal {
+    fn from_value(v: &Value) -> Result<Self, ShellError> {
+        match v {
+            Value {
+                value: UntaggedValue::Primitive(Primitive::Decimal(d)),
+                ..
+            } => Ok(d.clone()),
+            Value { tag, .. } => Err(ShellError::labeled_error(
+                "Can't convert to decimal",
+                "can't convert to decimal",
+                tag.span,
+            )),
+        }
+    }
+}
+
+impl FromValue for String {
+    fn from_value(v: &Value) -> Result<Self, ShellError> {
+        match v {
+            Value {
+                value: UntaggedValue::Primitive(Primitive::String(s)),
+                ..
+            } => Ok(s.clone()),
+            Value {
+                value: UntaggedValue::Primitive(Primitive::GlobPattern(s)),
+                ..
+            } => Ok(s.clone()),
+            Value {
+                value: UntaggedValue::Primitive(Primitive::FilePath(p)),
+                ..
+            } => Ok(p.to_string_lossy().to_string()),
+            Value { tag, .. } => Err(ShellError::labeled_error(
+                "Can't convert to string",
+                "can't convert to string",
+                tag.span,
+            )),
+        }
+    }
+}
+
+impl FromValue for Tagged<String> {
+    fn from_value(v: &Value) -> Result<Self, ShellError> {
+        let tag = v.tag.clone();
+        v.as_string().map(|s| s.tagged(tag))
+    }
+}
+
+impl FromValue for PathBuf {
+    fn from_value(v: &Value) -> Result<Self, ShellError> {
+        match v {
+            Value {
+                value: UntaggedValue::Primitive(Primitive::String(s)),
+                ..
+            } => Ok(PathBuf::from(s)),
+            Value {
+                value: UntaggedValue::Primitive(Primitive::FilePath(p)),
+                ..
+            } => Ok(p.clone()),
+            Value { tag, .. } => Err(ShellError::labeled_error(
+                "Can't convert to filepath",
+                "can't convert to filepath",
+                tag.span,
+            )),
+        }
+    }
+}
+
+impl FromValue for ColumnPath {
+    fn from_value(v: &Value) -> Result<Self, ShellError> {
+        match v {
+            Value {
+                value: UntaggedValue::Primitive(Primitive::ColumnPath(c)),
+                ..
+            } => Ok(c.clone()),
+            Value { tag, .. } => Err(ShellError::labeled_error(
+                "Can't convert to column path",
+                "can't convert to column path",
+                tag.span,
+            )),
+        }
+    }
+}
+
+impl FromValue for bool {
+    fn from_value(v: &Value) -> Result<Self, ShellError> {
+        match v {
+            Value {
+                value: UntaggedValue::Primitive(Primitive::Boolean(b)),
+                ..
+            } => Ok(*b),
+            Value { tag, .. } => Err(ShellError::labeled_error(
+                "Can't convert to boolean",
+                "can't convert to boolean",
+                tag.span,
+            )),
+        }
+    }
+}
+
+impl FromValue for Tagged<bool> {
+    fn from_value(v: &Value) -> Result<Self, ShellError> {
+        match v {
+            Value {
+                value: UntaggedValue::Primitive(Primitive::Boolean(b)),
+                tag,
+            } => Ok((*b).tagged(tag)),
+            Value { tag, .. } => Err(ShellError::labeled_error(
+                "Can't convert to boolean",
+                "can't convert to boolean",
+                tag.span,
+            )),
+        }
+    }
+}
+
+impl FromValue for DateTime<FixedOffset> {
+    fn from_value(v: &Value) -> Result<Self, ShellError> {
+        match v {
+            Value {
+                value: UntaggedValue::Primitive(Primitive::Date(d)),
+                ..
+            } => Ok(*d),
+            Value { tag, .. } => Err(ShellError::labeled_error(
+                "Can't convert to date",
+                "can't convert to date",
+                tag.span,
+            )),
+        }
+    }
+}
+
+impl FromValue for Range {
+    fn from_value(v: &Value) -> Result<Self, ShellError> {
+        match v {
+            Value {
+                value: UntaggedValue::Primitive(Primitive::Range(r)),
+                ..
+            } => Ok((**r).clone()),
+            Value { tag, .. } => Err(ShellError::labeled_error(
+                "Can't convert to range",
+                "can't convert to range",
+                tag.span,
+            )),
+        }
+    }
+}
+
+impl FromValue for Vec<u8> {
+    fn from_value(v: &Value) -> Result<Self, ShellError> {
+        match v {
+            Value {
+                value: UntaggedValue::Primitive(Primitive::Binary(b)),
+                ..
+            } => Ok(b.clone()),
+            Value {
+                value: UntaggedValue::Primitive(Primitive::String(s)),
+                ..
+            } => Ok(s.bytes().collect()),
+            Value { tag, .. } => Err(ShellError::labeled_error(
+                "Can't convert to binary data",
+                "can't convert to binary data",
+                tag.span,
+            )),
+        }
+    }
+}
+
+impl FromValue for Dictionary {
+    fn from_value(v: &Value) -> Result<Self, ShellError> {
+        match v {
+            Value {
+                value: UntaggedValue::Row(r),
+                ..
+            } => Ok(r.clone()),
+            Value { tag, .. } => Err(ShellError::labeled_error(
+                "Can't convert to row",
+                "can't convert to row",
+                tag.span,
+            )),
+        }
+    }
+}
+
+impl FromValue for CapturedBlock {
+    fn from_value(v: &Value) -> Result<Self, ShellError> {
+        match v {
+            Value {
+                value: UntaggedValue::Block(b),
+                ..
+            } => Ok((**b).clone()),
+            Value { tag, .. } => Err(ShellError::labeled_error(
+                "Can't convert to block",
+                "can't convert to block",
+                tag.span,
+            )),
+        }
+    }
+}
+
+impl FromValue for Vec<Value> {
+    fn from_value(v: &Value) -> Result<Self, ShellError> {
+        match v {
+            Value {
+                value: UntaggedValue::Table(t),
+                ..
+            } => Ok(t.clone()),
+            Value { tag, .. } => Err(ShellError::labeled_error(
+                "Can't convert to table",
+                "can't convert to table",
+                tag.span,
+            )),
+        }
+    }
+}

crates/nu-engine/src/lib.rs

@@ -10,6 +10,7 @@ mod evaluate;
 mod evaluation_context;
 mod example;
 pub mod filesystem;
+mod from_value;
 mod maybe_text_codec;
 pub mod plugin;
 mod print;
@@ -36,6 +37,7 @@ pub use crate::example::Example;
 pub use crate::filesystem::dir_info::{DirBuilder, DirInfo, FileInfo};
 pub use crate::filesystem::filesystem_shell::FilesystemShell;
 pub use crate::filesystem::path;
+pub use crate::from_value::FromValue;
 pub use crate::maybe_text_codec::{BufCodecReader, MaybeTextCodec, StringOrBinary};
 pub use crate::print::maybe_print_errors;
 pub use crate::runnable_context::RunnableContext;

crates/nu-engine/src/maybe_text_codec.rs

@@ -71,19 +71,6 @@ impl Default for MaybeTextCodec {
     }
 }
 
-// impl MaybeTextCodec {
-//     fn encode(&mut self, item: StringOrBinary, mut dst: &mut [u8]) {
-//         match item {
-//             StringOrBinary::String(s) => {
-//                 dst.put(s.as_bytes());
-//             }
-//             StringOrBinary::Binary(b) => {
-//                 dst.put(Bytes::from(b));
-//             }
-//         }
-//     }
-// }
-
 impl MaybeTextCodec {
     pub fn decode(&mut self, src: &[u8]) -> Result<Option<StringOrBinary>, ShellError> {
         if src.is_empty() {