[librsvg: 2/9] Replace duplicated num-or-percentage parse functions with helpers

[Federico Mena Quintero <federico src gnome org>]

commit ed210a28f26fa512d04c9aeae93f6a71db133595
Author: John Ledbetter <john ledbetter gmail com>
Date:   Wed May 19 15:32:01 2021 -0400

    Replace duplicated num-or-percentage parse functions with helpers
    
    Introduces `parse_num_or_percentage{,_clamped}` helpers, which are
    used by many different filter function parser functions.

 src/filter_func.rs | 40 ++++++++++++++++++++--------------------
 1 file changed, 20 insertions(+), 20 deletions(-)
---
diff --git a/src/filter_func.rs b/src/filter_func.rs
index 8ce3725e..4ac29065 100644
--- a/src/filter_func.rs
+++ b/src/filter_func.rs
@@ -91,46 +91,46 @@ fn parse_blur<'i>(parser: &mut Parser<'i, '_>) -> Result<FilterFunction, ParseEr
     }))
 }
 
-#[allow(clippy::unnecessary_wraps)]
-fn parse_grayscale<'i>(parser: &mut Parser<'i, '_>) -> Result<FilterFunction, ParseError<'i>> {
-    let proportion = match parser.try_parse(|p| NumberOrPercentage::parse(p)) {
+/// Reads an optional number or percentage from the parser.
+/// Negative numbers are not allowed.
+fn parse_num_or_percentage<'i>(parser: &mut Parser<'i, '_>) -> Option<f64> {
+    match parser.try_parse(|p| NumberOrPercentage::parse(p)) {
         Ok(NumberOrPercentage { value }) if value < 0.0 => None,
-        Ok(NumberOrPercentage { value }) => Some(value.clamp(0.0, 1.0)),
+        Ok(NumberOrPercentage { value }) => Some(value),
         Err(_) => None,
-    };
+    }
+}
+
+/// Reads an optional number or percentage from the parser, returning a value clamped to [0, 1].
+/// Negative numbers are not allowed.
+fn parse_num_or_percentage_clamped<'i>(parser: &mut Parser<'i, '_>) -> Option<f64> {
+    parse_num_or_percentage(parser).map(|value| value.clamp(0.0, 1.0))
+}
+
+#[allow(clippy::unnecessary_wraps)]
+fn parse_grayscale<'i>(parser: &mut Parser<'i, '_>) -> Result<FilterFunction, ParseError<'i>> {
+    let proportion = parse_num_or_percentage_clamped(parser);
 
     Ok(FilterFunction::Grayscale(Grayscale { proportion }))
 }
 
 #[allow(clippy::unnecessary_wraps)]
 fn parse_opacity<'i>(parser: &mut Parser<'i, '_>) -> Result<FilterFunction, ParseError<'i>> {
-    let proportion = match parser.try_parse(|p| NumberOrPercentage::parse(p)) {
-        Ok(NumberOrPercentage { value }) if value < 0.0 => None,
-        Ok(NumberOrPercentage { value }) => Some(value.clamp(0.0, 1.0)),
-        Err(_) => None,
-    };
+    let proportion = parse_num_or_percentage_clamped(parser);
 
     Ok(FilterFunction::Opacity(Opacity { proportion }))
 }
 
 #[allow(clippy::unnecessary_wraps)]
 fn parse_saturate<'i>(parser: &mut Parser<'i, '_>) -> Result<FilterFunction, ParseError<'i>> {
-    let proportion = match parser.try_parse(|p| NumberOrPercentage::parse(p)) {
-        Ok(NumberOrPercentage { value }) if value < 0.0 => None,
-        Ok(NumberOrPercentage { value }) => Some(value),
-        Err(_) => None,
-    };
+    let proportion = parse_num_or_percentage(parser);
 
     Ok(FilterFunction::Saturate(Saturate { proportion }))
 }
 
 #[allow(clippy::unnecessary_wraps)]
 fn parse_sepia<'i>(parser: &mut Parser<'i, '_>) -> Result<FilterFunction, ParseError<'i>> {
-    let proportion = match parser.try_parse(|p| NumberOrPercentage::parse(p)) {
-        Ok(NumberOrPercentage { value }) if value < 0.0 => None,
-        Ok(NumberOrPercentage { value }) => Some(value.clamp(0.0, 1.0)),
-        Err(_) => None,
-    };
+    let proportion = parse_num_or_percentage_clamped(parser);
 
     Ok(FilterFunction::Sepia(Sepia { proportion }))
 }