From 2ce639e9bed74153e972b2ee441dd803db259fd1 Mon Sep 17 00:00:00 2001
From: ConnorSkees <39542938+ConnorSkees@users.noreply.github.com>
Date: Mon, 30 Mar 2020 10:42:13 -0400
Subject: [PATCH] implement > < >= <=

---
 src/value/mod.rs   | 43 ++++++++++++++++++++++++++++--
 src/value/parse.rs | 20 ++++++++++++++
 tests/ordering.rs  | 65 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 126 insertions(+), 2 deletions(-)
 create mode 100644 tests/ordering.rs

diff --git a/src/value/mod.rs b/src/value/mod.rs
index 7505860..8ac8fd5 100644
--- a/src/value/mod.rs
+++ b/src/value/mod.rs
@@ -1,10 +1,11 @@
 use std::fmt::{self, Display, Write};
 use std::iter::Iterator;
+use std::cmp::Ordering;
 
 use crate::color::Color;
 use crate::common::{Brackets, ListSeparator, Op, QuoteKind};
 use crate::error::SassResult;
-use crate::unit::Unit;
+use crate::unit::{Unit, UNIT_CONVERSION_TABLE};
 pub(crate) use number::Number;
 
 mod number;
@@ -183,7 +184,22 @@ impl Value {
                 Op::Mul => *lhs * *rhs,
                 Op::Div => *lhs / *rhs,
                 Op::Rem => *lhs % *rhs,
-                _ => Ok(Self::BinaryOp(lhs, op, rhs)),
+                Op::GreaterThan => match lhs.cmp(&rhs, op)? {
+                    Ordering::Greater  => Ok(Self::True),
+                    Ordering::Less | Ordering::Equal=> Ok(Self::False),
+                },
+                Op::GreaterThanEqual => match lhs.cmp(&rhs, op)? {
+                    Ordering::Greater | Ordering::Equal => Ok(Self::True),
+                    Ordering::Less => Ok(Self::False),
+                },
+                Op::LessThan => match lhs.cmp(&rhs, op)? {
+                    Ordering::Less  => Ok(Self::True),
+                    Ordering::Greater | Ordering::Equal=> Ok(Self::False),
+                },
+                Op::LessThanEqual => match lhs.cmp(&rhs, op)? {
+                    Ordering::Less | Ordering::Equal => Ok(Self::True),
+                    Ordering::Greater => Ok(Self::False),
+                },
             },
             Self::Paren(v) => v.eval(),
             Self::UnaryOp(op, val) => match op {
@@ -194,4 +210,27 @@ impl Value {
             _ => Ok(self),
         }
     }
+
+    pub fn cmp(&self, other: &Self, op: Op) -> SassResult<Ordering> {
+        Ok(match self {
+            Self::Dimension(num, ref unit) => match other {
+                Self::Dimension(num2, unit2) => {
+                    if !unit.comparable(&unit2) {
+                        return Err(format!("Incompatible units {} and {}.", unit2, unit).into());
+                    }
+                    if unit == unit2 {
+                        num.cmp(num2)
+                    } else if unit == &Unit::None {
+                        num.cmp(num2)
+                    } else if unit2 == &Unit::None {
+                        num.cmp(num2)
+                    } else {
+                        num.cmp(&(num2.clone() * UNIT_CONVERSION_TABLE[&unit.to_string()][&unit2.to_string()].clone()))
+                    }
+                }
+                _ => return Err(format!("Undefined operation \"{} {} {}\".", self, op, other).into()),
+            },
+            _ => return Err(format!("Undefined operation \"{} {} {}\".", self, op, other).into())
+        })
+    }
 }
diff --git a/src/value/parse.rs b/src/value/parse.rs
index 972ff0b..86ee9f0 100644
--- a/src/value/parse.rs
+++ b/src/value/parse.rs
@@ -188,6 +188,26 @@ impl Value {
                     return Err("expected \"=\".".into());
                 }
             }
+            q @ '>' | q @ '<' => {
+                toks.next();
+                let op = if toks.peek().unwrap().kind == '=' {
+                    toks.next();
+                    match q {
+                        '>' => Op::GreaterThanEqual,
+                        '<' => Op::LessThanEqual,
+                        _ => unreachable!()
+                    }
+                } else {
+                    match q {
+                        '>' => Op::GreaterThan,
+                        '<' => Op::LessThan,
+                        _ => unreachable!()
+                    }
+                };
+                devour_whitespace(toks);                
+                let right = Self::from_tokens(toks, scope, super_selector)?;
+                Ok(Value::BinaryOp(Box::new(left), op, Box::new(right)))
+            }
             '!' => {
                 toks.next();
                 if toks.peek().unwrap().kind == '=' {
diff --git a/tests/ordering.rs b/tests/ordering.rs
new file mode 100644
index 0000000..93db708
--- /dev/null
+++ b/tests/ordering.rs
@@ -0,0 +1,65 @@
+#![cfg(test)]
+
+#[macro_use]
+mod macros;
+
+test!(
+    greater_than_or_equal_is_greater,
+    "a {\n  color: 2 >= 1;\n}\n",
+    "a {\n  color: true;\n}\n"
+);
+test!(
+    greater_than_or_equal_is_equal,
+    "a {\n  color: 1 >= 1;\n}\n",
+    "a {\n  color: true;\n}\n"
+);
+test!(
+    greater_than_or_equal_is_less,
+    "a {\n  color: 0 >= 1;\n}\n",
+    "a {\n  color: false;\n}\n"
+);
+test!(
+    greater_than_is_greater,
+    "a {\n  color: 2 > 1;\n}\n",
+    "a {\n  color: true;\n}\n"
+);
+test!(
+    greater_than_is_equal,
+    "a {\n  color: 1 > 1;\n}\n",
+    "a {\n  color: false;\n}\n"
+);
+test!(
+    greater_than_is_less,
+    "a {\n  color: 0 > 1;\n}\n",
+    "a {\n  color: false;\n}\n"
+);
+test!(
+    less_than_or_equal_is_greater,
+    "a {\n  color: 2 <= 1;\n}\n",
+    "a {\n  color: false;\n}\n"
+);
+test!(
+    less_than_or_equal_is_equal,
+    "a {\n  color: 1 <= 1;\n}\n",
+    "a {\n  color: true;\n}\n"
+);
+test!(
+    less_than_or_equal_is_less,
+    "a {\n  color: 0 <= 1;\n}\n",
+    "a {\n  color: true;\n}\n"
+);
+test!(
+    less_than_is_greater,
+    "a {\n  color: 2 < 1;\n}\n",
+    "a {\n  color: false;\n}\n"
+);
+test!(
+    less_than_is_equal,
+    "a {\n  color: 1 < 1;\n}\n",
+    "a {\n  color: false;\n}\n"
+);
+test!(
+    less_than_is_less,
+    "a {\n  color: 0 < 1;\n}\n",
+    "a {\n  color: true;\n}\n"
+);