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.

src/evaluate/evaluator.rs

@@ -1,5 +1,6 @@
 use crate::data::base::Block;
 use crate::errors::ArgumentError;
+use crate::evaluate::operator::apply_operator;
 use crate::parser::hir::path::{ColumnPath, RawPathMember};
 use crate::parser::{
     hir::{self, Expression, RawExpression},
@@ -79,8 +80,8 @@ pub(crate) fn evaluate_baseline_expr(
 
             trace!("left={:?} right={:?}", left.item, right.item);
 
-            match left.compare(binary.op(), &*right) {
-                Ok(result) => Ok(Value::boolean(result).tagged(tag)),
+            match apply_operator(binary.op(), &*left, &*right) {
+                Ok(result) => Ok(result.tagged(tag)),
                 Err((left_type, right_type)) => Err(ShellError::coerce_error(
                     left_type.spanned(binary.left().span),
                     right_type.spanned(binary.right().span),

src/evaluate/mod.rs

@@ -1,3 +1,4 @@
 pub(crate) mod evaluator;
+pub(crate) mod operator;
 
 pub(crate) use evaluator::{evaluate_baseline_expr, Scope};

src/evaluate/operator.rs

@@ -0,0 +1,33 @@
+use crate::data::Primitive;
+use crate::data::Value;
+use crate::parser::Operator;
+use crate::traits::ShellTypeName;
+use std::ops::Not;
+
+pub fn apply_operator(
+    op: &Operator,
+    left: &Value,
+    right: &Value,
+) -> Result<Value, (&'static str, &'static str)> {
+    match *op {
+        Operator::Equal
+        | Operator::NotEqual
+        | Operator::LessThan
+        | Operator::GreaterThan
+        | Operator::LessThanOrEqual
+        | Operator::GreaterThanOrEqual => left.compare(op, right).map(Value::boolean),
+        Operator::Dot => Ok(Value::boolean(false)),
+        Operator::Contains => contains(left, right).map(Value::boolean),
+        Operator::NotContains => contains(left, right).map(Not::not).map(Value::boolean),
+    }
+}
+
+fn contains(left: &Value, right: &Value) -> Result<bool, (&'static str, &'static str)> {
+    if let (Value::Primitive(Primitive::String(l)), Value::Primitive(Primitive::String(r))) =
+        (left, right)
+    {
+        Ok(l.contains(r))
+    } else {
+        Err((left.type_name(), right.type_name()))
+    }
+}

src/parser/parse/operator.rs

@@ -12,6 +12,8 @@ pub enum Operator {
     LessThanOrEqual,
     GreaterThanOrEqual,
     Dot,
+    Contains,
+    NotContains,
 }
 
 impl FormatDebug for Operator {
@@ -34,6 +36,8 @@ impl Operator {
             Operator::LessThanOrEqual => "<=",
             Operator::GreaterThanOrEqual => ">=",
             Operator::Dot => ".",
+            Operator::Contains => "=~",
+            Operator::NotContains => "!~",
         }
     }
 }
@@ -55,6 +59,8 @@ impl FromStr for Operator {
             "<=" => Ok(Operator::LessThanOrEqual),
             ">=" => Ok(Operator::GreaterThanOrEqual),
             "." => Ok(Operator::Dot),
+            "=~" => Ok(Operator::Contains),
+            "!~" => Ok(Operator::NotContains),
             _ => Err(()),
         }
     }

src/parser/parse/parser.rs

@@ -59,7 +59,7 @@ macro_rules! operator {
         #[tracable_parser]
         pub fn $name(input: NomSpan) -> IResult<NomSpan, TokenNode> {
             let start = input.offset;
-            let (input, tag) = tag(stringify!($token))(input)?;
+            let (input, tag) = tag($token)(input)?;
             let end = input.offset;
 
             Ok((
@@ -70,13 +70,15 @@ macro_rules! operator {
     };
 }
 
-operator! { gt:  >  }
-operator! { lt:  <  }
-operator! { gte: >= }
-operator! { lte: <= }
-operator! { eq:  == }
-operator! { neq: != }
-operator! { dot: . }
+operator! { gt:  ">"  }
+operator! { lt:  "<"  }
+operator! { gte: ">=" }
+operator! { lte: "<=" }
+operator! { eq:  "==" }
+operator! { neq: "!=" }
+operator! { dot: "." }
+operator! { cont: "=~" }
+operator! { ncont: "!~" }
 
 #[derive(Debug, Clone, Eq, PartialEq, Hash, Ord, PartialOrd, Serialize, Deserialize)]
 pub enum Number {
@@ -228,7 +230,7 @@ pub fn raw_number(input: NomSpan) -> IResult<NomSpan, Spanned<RawNumber>> {
 
 #[tracable_parser]
 pub fn operator(input: NomSpan) -> IResult<NomSpan, TokenNode> {
-    let (input, operator) = alt((gte, lte, neq, gt, lt, eq))(input)?;
+    let (input, operator) = alt((gte, lte, neq, gt, lt, eq, cont, ncont))(input)?;
 
     Ok((input, operator))
 }
@@ -830,6 +832,16 @@ mod tests {
             <nodes>
             "!=" -> b::token_list(vec![b::op("!=")])
         }
+
+        equal_tokens! {
+            <nodes>
+            "=~" -> b::token_list(vec![b::op("=~")])
+        }
+
+        equal_tokens! {
+            <nodes>
+            "!~" -> b::token_list(vec![b::op("!~")])
+        }
     }
 
     #[test]

tests/filter_where_tests.rs

@@ -0,0 +1,112 @@
+mod helpers;
+
+use helpers as h;
+
+#[test]
+fn test_compare() {
+    let actual = nu!(
+        cwd: "tests/fixtures/formats", h::pipeline(
+        r#"
+            open sample.db
+            | where table_name == ints
+            | get table_values
+            | first 4
+            | where z > 4200
+            | get z
+            | echo $it
+        "#
+    ));
+
+    assert_eq!(actual, "4253");
+
+    let actual = nu!(
+        cwd: "tests/fixtures/formats", h::pipeline(
+        r#"
+            open sample.db
+            | where table_name == ints
+            | get table_values
+            | first 4
+            | where z >= 4253
+            | get z
+            | echo $it
+        "#
+    ));
+
+    assert_eq!(actual, "4253");
+
+    let actual = nu!(
+        cwd: "tests/fixtures/formats", h::pipeline(
+        r#"
+            open sample.db
+            | where table_name == ints
+            | get table_values
+            | first 4
+            | where z < 10
+            | get z
+            | echo $it
+        "#
+    ));
+
+    assert_eq!(actual, "1");
+
+    let actual = nu!(
+        cwd: "tests/fixtures/formats", h::pipeline(
+        r#"
+            open sample.db
+            | where table_name == ints
+            | get table_values
+            | first 4
+            | where z <= 1
+            | get z
+            | echo $it
+        "#
+    ));
+
+    assert_eq!(actual, "1");
+
+    let actual = nu!(
+        cwd: "tests/fixtures/formats", h::pipeline(
+        r#"
+            open sample.db
+            | where table_name == ints
+            | get table_values
+            | where z != 1
+            | first 1
+            | get z
+            | echo $it
+        "#
+    ));
+
+    assert_eq!(actual, "42");
+}
+
+#[test]
+fn test_contains() {
+    let actual = nu!(
+        cwd: "tests/fixtures/formats", h::pipeline(
+        r#"
+            open sample.db
+            | where table_name == strings
+            | get table_values
+            | where x =~ ell
+            | count
+            | echo $it
+        "#
+    ));
+
+    assert_eq!(actual, "4");
+
+    let actual = nu!(
+        cwd: "tests/fixtures/formats", h::pipeline(
+        r#"
+            open sample.db
+            | where table_name == strings
+            | get table_values
+            | where x !~ ell
+            | count
+            | echo $it
+        "#
+    ));
+
+    assert_eq!(actual, "2");
+}