style: add flex shorthand parser

src/web/vaev-style/styles.h

@@ -7,8 +7,6 @@
 
 #include "base.h"
 #include "computed.h"
-#include "karm-base/res.h"
-#include "karm-logger/logger.h"
 #include "values.h"
 
 // https://www.w3.org/TR/CSS22/propidx.html
@@ -870,6 +868,85 @@ struct FlexFlowProp {
     }
 };
 
+// https://www.w3.org/TR/css-flexbox-1/#propdef-flex
+struct FlexProp {
+    Tuple<FlexBasis, Number, Number> value = initial();
+
+    static Tuple<FlexBasis, Number, Number> initial() {
+        return {
+            Width{Width::AUTO},
+            0,
+            1,
+        };
+    }
+
+    static constexpr Str name() { return "flex"; }
+
+    void apply(Computed &c) const {
+        c.flex.cow().basis = value.v0;
+        c.flex.cow().grow = value.v1;
+        c.flex.cow().shrink = value.v2;
+    }
+
+    Res<> parse(Cursor<Css::Sst> &c) {
+        if (c.ended())
+            return Error::invalidData("unexpected end of input");
+
+        if (c.skip(Css::Token::ident("none"))) {
+            value.v0 = Width{Width::AUTO};
+            value.v1 = value.v2 = 0;
+            return Ok();
+        } else if (c.skip(Css::Token::ident("initial"))) {
+            value.v0 = Width{Width::AUTO};
+            value.v1 = 0, value.v2 = 1;
+            return Ok();
+        }
+
+        auto parseGrowShrink = [&c]() -> Res<Tuple<Number, Number>> {
+            auto grow = parseValue<Number>(c);
+            if (not grow)
+                return Error::invalidData("expected flex item grow");
+
+            Number growValue = grow.unwrap();
+
+            Number shrinkValue;
+            auto shrink = parseValue<Number>(c);
+            if (shrink)
+                shrinkValue = shrink.unwrap();
+            else
+                shrinkValue = 1;
+            return Ok(Tuple{growValue, shrinkValue});
+        };
+
+        auto maybeGrowShrinkValues = parseGrowShrink();
+        if (maybeGrowShrinkValues) {
+            auto growShrinkValues = maybeGrowShrinkValues.unwrap();
+            value.v1 = growShrinkValues.v0, value.v2 = growShrinkValues.v1;
+
+            auto basis = parseValue<FlexBasis>(c);
+            if (basis)
+                value.v0 = basis.unwrap();
+            else
+                value.v0 = FlexBasis(Width(Length(0, Length::Unit::PX)));
+        } else {
+            auto basis = parseValue<FlexBasis>(c);
+            if (basis)
+                value.v0 = basis.unwrap();
+            else
+                return Error::invalidData("expected flex item grow or basis");
+
+            maybeGrowShrinkValues = parseGrowShrink();
+            if (maybeGrowShrinkValues) {
+                auto growShrinkValues = maybeGrowShrinkValues.unwrap();
+                value.v1 = growShrinkValues.v0, value.v2 = growShrinkValues.v1;
+            } else {
+                value.v1 = value.v2 = 1;
+            }
+        }
+        return Ok();
+    }
+};
+
 // MARK: Fonts -----------------------------------------------------------------
 
 // https://www.w3.org/TR/css-fonts-4/#font-family-prop
@@ -1592,6 +1669,7 @@ using _StyleProp = Union<
     FlexShrinkProp,
     FlexWrapProp,
     FlexFlowProp,
+    FlexProp,
 
     // Font
     FontFamilyProp,