From be3e55c079fe43f8f35ebe5add00fd05ef912f79 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?PedroGon=C3=A7aloCorreia?= <goncalerta@gmail.com>
Date: Sat, 13 Oct 2018 23:26:20 +0100
Subject: [PATCH] feat(liquid_filters): add filters "at_least" and "at_most"

Add two filters specified in the Liquid tutorial:
- at_least
- at_most
---
 src/filters/math.rs | 84 +++++++++++++++++++++++++++++++++++++++++++++
 src/filters/mod.rs  |  2 +-
 src/parser.rs       |  2 ++
 3 files changed, 87 insertions(+), 1 deletion(-)

diff --git a/src/filters/math.rs b/src/filters/math.rs
index a1e4b498f..4c54333b7 100644
--- a/src/filters/math.rs
+++ b/src/filters/math.rs
@@ -17,6 +17,52 @@ pub fn abs(input: &Value, args: &[Value]) -> FilterResult {
     }
 }
 
+/// Limits a number to a minimum value.
+pub fn at_least(input: &Value, args: &[Value]) -> FilterResult {
+    check_args_len(args, 1, 0)?;
+    let input = input
+        .as_scalar()
+        .ok_or_else(|| invalid_input("Number expected"))?;
+
+    let max_value = args[0]
+        .as_scalar()
+        .ok_or_else(|| invalid_argument(0, "Number expected"))?;
+
+    let result = input
+        .to_integer()
+        .and_then(|i| max_value.to_integer().map(|max| Value::scalar(i.max(max))))
+        .or_else(|| {
+            input
+                .to_float()
+                .and_then(|i| max_value.to_float().map(|max| Value::scalar(i.max(max))))
+        }).ok_or_else(|| invalid_argument(0, "Number expected"))?;
+
+    Ok(result)
+}
+
+/// Limits a number to a maximum value.
+pub fn at_most(input: &Value, args: &[Value]) -> FilterResult {
+    check_args_len(args, 1, 0)?;
+    let input = input
+        .as_scalar()
+        .ok_or_else(|| invalid_input("Number expected"))?;
+
+    let max_value = args[0]
+        .as_scalar()
+        .ok_or_else(|| invalid_argument(0, "Number expected"))?;
+
+    let result = input
+        .to_integer()
+        .and_then(|i| max_value.to_integer().map(|max| Value::scalar(i.min(max))))
+        .or_else(|| {
+            input
+                .to_float()
+                .and_then(|i| max_value.to_float().map(|max| Value::scalar(i.min(max))))
+        }).ok_or_else(|| invalid_argument(0, "Number expected"))?;
+
+    Ok(result)
+}
+
 pub fn plus(input: &Value, args: &[Value]) -> FilterResult {
     check_args_len(args, 1, 0)?;
 
@@ -199,6 +245,44 @@ mod tests {
         assert_eq!(unit!(abs, tos!("-19.86"), &[]), Value::scalar(19.86f64));
     }
     #[test]
+    fn unit_at_least() {
+        assert_eq!(
+            unit!(at_least, Value::scalar(4f64), &[Value::scalar(5f64)]),
+            Value::scalar(5f64)
+        );
+        assert_eq!(
+            unit!(at_least, Value::scalar(4f64), &[Value::scalar(3f64)]),
+            Value::scalar(4f64)
+        );
+        assert_eq!(
+            unit!(at_least, Value::scalar(21.5), &[Value::scalar(2.25)]),
+            Value::scalar(21.5)
+        );
+        assert_eq!(
+            unit!(at_least, Value::scalar(21.5), &[Value::scalar(42.25)]),
+            Value::scalar(42.25)
+        );
+    }
+    #[test]
+    fn unit_at_most() {
+        assert_eq!(
+            unit!(at_most, Value::scalar(4f64), &[Value::scalar(5f64)]),
+            Value::scalar(4f64)
+        );
+        assert_eq!(
+            unit!(at_most, Value::scalar(4f64), &[Value::scalar(3f64)]),
+            Value::scalar(3f64)
+        );
+        assert_eq!(
+            unit!(at_most, Value::scalar(21.5), &[Value::scalar(2.25)]),
+            Value::scalar(2.25)
+        );
+        assert_eq!(
+            unit!(at_most, Value::scalar(21.5), &[Value::scalar(42.25)]),
+            Value::scalar(21.5)
+        );
+    }
+    #[test]
     fn unit_plus() {
         assert_eq!(
             unit!(plus, Value::scalar(2f64), &[Value::scalar(1f64)]),
diff --git a/src/filters/mod.rs b/src/filters/mod.rs
index f28f957ad..e60728a70 100644
--- a/src/filters/mod.rs
+++ b/src/filters/mod.rs
@@ -7,7 +7,7 @@ pub use self::date::date;
 #[cfg(feature = "extra-filters")]
 pub use self::date::date_in_tz;
 pub use self::html::{escape, escape_once, newline_to_br, strip_html};
-pub use self::math::{abs, divided_by, minus, modulo, plus, times};
+pub use self::math::{abs, at_least, at_most, divided_by, minus, modulo, plus, times};
 pub use self::url::{url_decode, url_encode};
 
 use std::borrow::Cow;
diff --git a/src/parser.rs b/src/parser.rs
index 71d1a0215..5b8f24c68 100644
--- a/src/parser.rs
+++ b/src/parser.rs
@@ -58,6 +58,8 @@ impl ParserBuilder {
     pub fn liquid_filters(self) -> Self {
         self.filter("abs", filters::abs as interpreter::FnFilterValue)
             .filter("append", filters::append as interpreter::FnFilterValue)
+            .filter("at_least", filters::at_least as interpreter::FnFilterValue)
+            .filter("at_most", filters::at_most as interpreter::FnFilterValue)
             .filter(
                 "capitalize",
                 filters::capitalize as interpreter::FnFilterValue,