Add =~ and !~ operators on strings

`left =~ right` return true if left contains right, using Rust's
`String::contains`. `!~` is the negated version.

A new `apply_operator` function is added which decouples evaluation from
`Value::compare`. This returns a `Value` and opens the door to
implementing `+` for example, though it wouldn't be useful immediately.

The `operator!` macro had to be changed slightly as it would choke on
`~` in arguments.

crates/nu-parser/src/debug.rs

@@ -1,51 +0,0 @@
-use nu_source::ShellAnnotation;
-use pretty::{Render, RenderAnnotated};
-use std::io;
-use termcolor::WriteColor;
-
-pub struct TermColored<'a, W> {
-    color_stack: Vec<ShellAnnotation>,
-    upstream: &'a mut W,
-}
-
-impl<'a, W> TermColored<'a, W> {
-    pub fn new(upstream: &'a mut W) -> TermColored<'a, W> {
-        TermColored {
-            color_stack: Vec::new(),
-            upstream,
-        }
-    }
-}
-
-impl<'a, W> Render for TermColored<'a, W>
-where
-    W: io::Write,
-{
-    type Error = io::Error;
-
-    fn write_str(&mut self, s: &str) -> io::Result<usize> {
-        self.upstream.write(s.as_bytes())
-    }
-
-    fn write_str_all(&mut self, s: &str) -> io::Result<()> {
-        self.upstream.write_all(s.as_bytes())
-    }
-}
-
-impl<'a, W> RenderAnnotated<ShellAnnotation> for TermColored<'a, W>
-where
-    W: WriteColor,
-{
-    fn push_annotation(&mut self, ann: &ShellAnnotation) -> Result<(), Self::Error> {
-        self.color_stack.push(*ann);
-        self.upstream.set_color(&(*ann).into())
-    }
-
-    fn pop_annotation(&mut self) -> Result<(), Self::Error> {
-        self.color_stack.pop();
-        match self.color_stack.last() {
-            Some(previous) => self.upstream.set_color(&(*previous).into()),
-            None => self.upstream.reset(),
-        }
-    }
-}

crates/nu-parser/src/hir.rs

@@ -13,13 +13,7 @@ use crate::parse::parser::Number;
 use crate::parse::unit::Unit;
 use derive_new::new;
 use getset::Getters;
-#[cfg(not(coloring_in_tokens))]
-use nu_errors::ShellError;
-#[cfg(not(coloring_in_tokens))]
-use nu_protocol::{EvaluatedArgs, Scope};
 use nu_protocol::{PathMember, ShellTypeName};
-#[cfg(not(coloring_in_tokens))]
-use nu_source::Text;
 use nu_source::{
     b, DebugDocBuilder, HasSpan, PrettyDebug, PrettyDebugWithSource, Span, Spanned, SpannedItem,
 };

crates/nu-parser/src/lib.rs

@@ -1,5 +1,4 @@
 pub mod commands;
-pub mod debug;
 pub mod hir;
 pub mod parse;
 pub mod parse_command;

crates/nu-source/src/lib.rs

@@ -11,5 +11,6 @@ pub use self::meta::{
 pub use self::pretty::{
     b, DebugDoc, DebugDocBuilder, PrettyDebug, PrettyDebugWithSource, ShellAnnotation,
 };
+pub use self::term_colored::TermColored;
 pub use self::text::Text;
 pub use self::tracable::{nom_input, NomSpan, TracableContext};