implement some of the more esoteric binary ops

addition, subtraction, and multiplication of functions and maps, along
with correct error messages and tests

src/value/ops.rs

@@ -186,9 +186,9 @@ impl Value {
                     return Err((
                         format!(
                             "Undefined operation \"{} {} {}\".",
-                            v.to_css_string(span)?,
+                            v.inspect(span)?,
                             op,
-                            other.to_css_string(span)?
+                            other.inspect(span)?
                         ),
                         span,
                     )
@@ -217,9 +217,9 @@ impl Value {
                 return Err((
                     format!(
                         "Undefined operation \"{} {} {}\".",
-                        self.to_css_string(span)?,
+                        self.inspect(span)?,
                         op,
-                        other.to_css_string(span)?
+                        other.inspect(span)?
                     ),
                     span,
                 )
@@ -256,14 +256,14 @@ impl Value {
         }
         let precedence = Op::Plus.precedence();
         Ok(match self {
-            Self::Map(..) => {
+            Self::Map(..) | Self::Function(..) => {
                 return Err((
                     format!("{} isn't a valid CSS value.", self.inspect(span)?),
                     span,
                 )
                     .into())
             }
-            Self::Function(..) | Self::ArgList(..) => todo!(),
+            Self::ArgList(..) => todo!(),
             Self::Important | Self::True | Self::False => match other {
                 Self::String(s, QuoteKind::Quoted) => Value::String(
                     format!("{}{}", self.to_css_string(span)?, s),
@@ -316,13 +316,20 @@ impl Value {
                     format!("{}{}{}", num, unit, other.to_css_string(span)?),
                     QuoteKind::None,
                 ),
+                Self::Map(..) | Self::Function(..) => {
+                    return Err((
+                        format!("{} isn't a valid CSS value.", other.inspect(span)?),
+                        span,
+                    )
+                        .into())
+                }
                 _ => {
                     return Err((
                         format!(
                             "Undefined operation \"{}{} + {}\".",
                             num,
                             unit,
-                            other.to_css_string(span)?
+                            other.inspect(span)?
                         ),
                         span,
                     )
@@ -338,11 +345,7 @@ impl Value {
                 ),
                 _ => {
                     return Err((
-                        format!(
+                        format!("Undefined operation \"{} + {}\".", c, other.inspect(span)?),
-                            "Undefined operation \"{} + {}\".",
-                            c,
-                            other.to_css_string(span)?
-                        ),
                         span,
                     )
                         .into())
@@ -396,7 +399,9 @@ impl Value {
         }
         let precedence = Op::Mul.precedence();
         Ok(match self {
-            Self::Null => todo!(),
+            Self::Null => {
+                Value::String(format!("-{}", other.to_css_string(span)?), QuoteKind::None)
+            }
             Self::Dimension(num, unit) => match other {
                 Self::Dimension(num2, unit2) => {
                     if !unit.comparable(&unit2) {
@@ -428,6 +433,13 @@ impl Value {
                     format!("{}{}-{}", num, unit, other.to_css_string(span)?),
                     QuoteKind::None,
                 ),
+                Self::Map(..) | Self::Function(..) => {
+                    return Err((
+                        format!("{} isn't a valid CSS value.", other.inspect(span)?),
+                        span,
+                    )
+                        .into())
+                }
                 _ => todo!(),
             },
             Self::Color(c) => match other {
@@ -437,11 +449,7 @@ impl Value {
                 Self::Null => Value::String(format!("{}-", c), QuoteKind::None),
                 Self::Dimension(..) | Self::Color(..) => {
                     return Err((
-                        format!(
+                        format!("Undefined operation \"{} - {}\".", c, other.inspect(span)?),
-                            "Undefined operation \"{} - {}\".",
-                            c,
-                            other.to_css_string(span)?
-                        ),
                         span,
                     )
                         .into())
@@ -544,7 +552,7 @@ impl Value {
                             "Undefined operation \"{}{} * {}\".",
                             num,
                             unit,
-                            other.to_css_string(span)?
+                            other.inspect(span)?
                         ),
                         span,
                     )
@@ -576,8 +584,8 @@ impl Value {
                 return Err((
                     format!(
                         "Undefined operation \"{} * {}\".",
-                        self.to_css_string(span)?,
+                        self.inspect(span)?,
-                        other.to_css_string(span)?
+                        other.inspect(span)?
                     ),
                     span,
                 )
@@ -628,11 +636,7 @@ impl Value {
                 Self::Null => Value::String(format!("{}/", c), QuoteKind::None),
                 Self::Dimension(..) | Self::Color(..) => {
                     return Err((
-                        format!(
+                        format!("Undefined operation \"{} / {}\".", c, other.inspect(span)?),
-                            "Undefined operation \"{} / {}\".",
-                            c,
-                            other.to_css_string(span)?
-                        ),
                         span,
                     )
                         .into())
@@ -720,8 +724,8 @@ impl Value {
                     return Err((
                         format!(
                             "Undefined operation \"{} % {}\".",
-                            Value::Dimension(n, u).to_css_string(span)?,
+                            Value::Dimension(n, u).inspect(span)?,
-                            other.to_css_string(span)?
+                            other.inspect(span)?
                         ),
                         span,
                     )
@@ -732,8 +736,8 @@ impl Value {
                 return Err((
                     format!(
                         "Undefined operation \"{} % {}\".",
-                        self.to_css_string(span)?,
+                        self.inspect(span)?,
-                        other.to_css_string(span)?
+                        other.inspect(span)?
                     ),
                     span,
                 )

tests/addition.rs

@@ -278,3 +278,21 @@ test!(
     "a {\n  color: 1+/2;\n}\n",
     "a {\n  color: 1/2;\n}\n"
 );
+error!(
+    map_lhs_add,
+    "a {color: (a: b) + 1;}", "Error: (a: b) isn't a valid CSS value."
+);
+error!(
+    map_rhs_add,
+    "a {color: 1 + (a: b);}", "Error: (a: b) isn't a valid CSS value."
+);
+error!(
+    function_lhs_add,
+    "a {color: get-function(lighten) + 1;}",
+    "Error: get-function(\"lighten\") isn't a valid CSS value."
+);
+error!(
+    function_rhs_add,
+    "a {color: 1 + get-function(lighten);}",
+    "Error: get-function(\"lighten\") isn't a valid CSS value."
+);

tests/error.rs

@@ -167,11 +167,3 @@ error!(
     operator_mul,
     "a {color: 5 - *;}", "Error: Expected expression."
 );
-error!(
-    map_lhs_add,
-    "a {color: (a: b) + 1;}", "Error: (a: b) isn't a valid CSS value."
-);
-error!(
-    map_rhs_add,
-    "a {color: 1 + (a: b);}", "Error: (a: b) isn't a valid CSS value."
-);

tests/multiplication.rs

@@ -0,0 +1,23 @@
+#![cfg(test)]
+
+#[macro_use]
+mod macros;
+
+error!(
+    map_lhs_mul,
+    "a {color: (a: b) * 1;}", "Error: Undefined operation \"(a: b) * 1\"."
+);
+error!(
+    map_rhs_mul,
+    "a {color: 1 * (a: b);}", "Error: Undefined operation \"1 * (a: b)\"."
+);
+error!(
+    function_lhs_mul,
+    "a {color: get-function(lighten) * 1;}",
+    "Error: Undefined operation \"get-function(\"lighten\") * 1\"."
+);
+error!(
+    function_rhs_mul,
+    "a {color: 1 * get-function(lighten);}",
+    "Error: Undefined operation \"1 * get-function(\"lighten\")\"."
+);

tests/subtraction.rs

@@ -214,3 +214,36 @@ test!(
     "a {\n  color: 1em- 0.0em;\n}\n",
     "a {\n  color: 1em- 0em;\n}\n"
 );
+test!(
+    null_minus_number,
+    "a {\n  color: null - 1;\n}\n",
+    "a {\n  color: -1;\n}\n"
+);
+test!(
+    null_minus_unquoted_string,
+    "a {\n  color: null - foo;\n}\n",
+    "a {\n  color: -foo;\n}\n"
+);
+error!(
+    null_minus_function,
+    "a {\n  color: null - get-function(lighten);\n}\n",
+    "Error: get-function(\"lighten\") isn't a valid CSS value."
+);
+error!(
+    map_lhs_sub,
+    "a {color: (a: b) - 1;}", "Error: (a: b) isn't a valid CSS value."
+);
+error!(
+    map_rhs_sub,
+    "a {color: 1 - (a: b);}", "Error: (a: b) isn't a valid CSS value."
+);
+error!(
+    function_lhs_sub,
+    "a {color: get-function(lighten) - 1;}",
+    "Error: get-function(\"lighten\") isn't a valid CSS value."
+);
+error!(
+    function_rhs_sub,
+    "a {color: 1 - get-function(lighten);}",
+    "Error: get-function(\"lighten\") isn't a valid CSS value."
+);