diff --git a/src/uu/tr/src/operation.rs b/src/uu/tr/src/operation.rs
index 960ab7ada..2ff43b2a5 100644
--- a/src/uu/tr/src/operation.rs
+++ b/src/uu/tr/src/operation.rs
@@ -26,10 +26,132 @@ mod unicode_table {
     pub static BLANK: &'static [char] = &[SPACE, HT];
 }
 
+struct Repeat(char);
+
+impl Repeat {
+    fn new(element: char) -> Repeat {
+        Repeat(element)
+    }
+}
+
+impl Iterator for Repeat {
+    type Item = char;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        Some(self.0)
+    }
+
+    fn last(self) -> Option<Self::Item> {
+        Some(self.0)
+    }
+
+    fn any<F>(&mut self, mut f: F) -> bool
+    where
+        Self: Sized,
+        F: FnMut(Self::Item) -> bool,
+    {
+        f(self.0)
+    }
+}
+
+fn truncate_iterator<T>(input: Option<usize>) -> impl Fn((usize, T)) -> Option<T> {
+    move |(idx, c)| match input {
+        Some(s) => match s.cmp(&idx) {
+            std::cmp::Ordering::Greater => Some(c),
+            _ => None,
+        },
+        None => Some(c),
+    }
+}
+
+#[derive(Debug, Clone, Copy)]
 pub enum Sequence {
     Char(char),
-    CharRange(Box<dyn Iterator<Item = char>>),
+    CharRange(u32, u32),
     CharStar(char),
+    CharRepeat(char, usize),
+    Alnum,
+    Alpha,
+    Blank,
+    Control,
+    Digit,
+    Graph,
+    Lower,
+    Print,
+    Punct,
+    Space,
+    Upper,
+    Xdigit,
+}
+
+impl Sequence {
+    pub fn flatten(&self) -> Box<dyn Iterator<Item = char>> {
+        match self {
+            Sequence::Char(c) => Box::new(std::iter::once(*c)),
+            Sequence::CharRange(l, r) => Box::new((*l..=*r).flat_map(char::from_u32)),
+            Sequence::CharStar(c) => Box::new(Repeat::new(*c)),
+            Sequence::CharRepeat(c, n) => Box::new(Repeat::new(*c).take(*n)),
+            Sequence::Alnum => Box::new(('0'..='9').chain('A'..='Z').chain('a'..='z')),
+            Sequence::Alpha => Box::new(('A'..='Z').chain('a'..='z')),
+            Sequence::Blank => Box::new(unicode_table::BLANK.into_iter().cloned()),
+            Sequence::Control => Box::new(
+                (0..=31)
+                    .chain(std::iter::once(127))
+                    .flat_map(char::from_u32),
+            ),
+            Sequence::Digit => Box::new('0'..='9'),
+            Sequence::Graph => Box::new(
+                (48..=57) // digit
+                    .chain(65..=90) // uppercase
+                    .chain(97..=122) // lowercase
+                    // punctuations
+                    .chain(33..=47)
+                    .chain(58..=64)
+                    .chain(91..=96)
+                    .chain(123..=126)
+                    .chain(std::iter::once(32)) // space
+                    .flat_map(char::from_u32),
+            ),
+            Sequence::Lower => Box::new('a'..='z'),
+            Sequence::Print => Box::new(
+                (48..=57) // digit
+                    .chain(65..=90) // uppercase
+                    .chain(97..=122) // lowercase
+                    // punctuations
+                    .chain(33..=47)
+                    .chain(58..=64)
+                    .chain(91..=96)
+                    .chain(123..=126)
+                    .flat_map(char::from_u32),
+            ),
+            Sequence::Punct => Box::new(
+                (33..=47)
+                    .chain(58..=64)
+                    .chain(91..=96)
+                    .chain(123..=126)
+                    .flat_map(char::from_u32),
+            ),
+            Sequence::Space => Box::new(unicode_table::SPACES.into_iter().cloned()),
+            Sequence::Upper => Box::new('A'..='Z'),
+            Sequence::Xdigit => Box::new(('0'..='9').chain('A'..='F').chain('a'..='f')),
+        }
+    }
+
+    pub fn last(&self) -> Option<char> {
+        match self {
+            Sequence::CharStar(c) => Some(*c),
+            // TODO: Can be optimized further...
+            rest => rest.flatten().last(),
+        }
+    }
+
+    pub fn len(&self) -> Option<usize> {
+        match self {
+            Sequence::CharStar(_) => None,
+            // TODO: Is there a fix for this?
+            rest => Some(rest.flatten().count()),
+        }
+    }
 }
 
 impl Sequence {
@@ -70,16 +192,6 @@ impl Sequence {
         .unwrap()
     }
 
-    pub fn dissolve(self) -> Box<dyn Iterator<Item = char>> {
-        match self {
-            Sequence::Char(c) => Box::new(std::iter::once(c)),
-            Sequence::CharRange(r) => r,
-            Sequence::CharStar(c) => Box::new(std::iter::repeat(c)),
-        }
-    }
-
-    /// Sequence parsers
-
     fn parse_char(input: &str) -> IResult<&str, Sequence> {
         anychar(input).map(|(l, r)| (l, Sequence::Char(r)))
     }
@@ -115,7 +227,7 @@ impl Sequence {
         separated_pair(anychar, tag("-"), anychar)(input).map(|(l, (a, b))| {
             (l, {
                 let (start, end) = (u32::from(a), u32::from(b));
-                Sequence::CharRange(Box::new((start..=end).filter_map(std::char::from_u32)))
+                Sequence::CharRange(start, end)
             })
         })
     }
@@ -129,7 +241,7 @@ impl Sequence {
         .map(|(l, (a, b))| {
             (l, {
                 let (start, end) = (u32::from(a), u32::from(b));
-                Sequence::CharRange(Box::new((start..=end).filter_map(std::char::from_u32)))
+                Sequence::CharRange(start, end)
             })
         })
     }
@@ -143,7 +255,7 @@ impl Sequence {
         .map(|(l, (a, b))| {
             (l, {
                 let (start, end) = (u32::from_str_radix(a, 8).unwrap(), u32::from(b));
-                Sequence::CharRange(Box::new((start..=end).filter_map(std::char::from_u32)))
+                Sequence::CharRange(start, end)
             })
         })
     }
@@ -157,7 +269,7 @@ impl Sequence {
         .map(|(l, (a, b))| {
             (l, {
                 let (start, end) = (u32::from(a), u32::from_str_radix(b, 8).unwrap());
-                Sequence::CharRange(Box::new((start..=end).filter_map(std::char::from_u32)))
+                Sequence::CharRange(start, end)
             })
         })
     }
@@ -174,7 +286,7 @@ impl Sequence {
                     u32::from_str_radix(a, 8).unwrap(),
                     u32::from_str_radix(b, 8).unwrap(),
                 );
-                Sequence::CharRange(Box::new((start..=end).filter_map(std::char::from_u32)))
+                Sequence::CharRange(start, end)
             })
         })
     }
@@ -189,136 +301,55 @@ impl Sequence {
             separated_pair(anychar, tag("*"), digit1),
             tag("]"),
         )(input)
-        .map(|(l, (c, n))| {
-            (
-                l,
-                Sequence::CharRange(Box::new(std::iter::repeat(c).take(n.parse().unwrap()))),
-            )
-        })
+        .map(|(l, (c, n))| (l, Sequence::CharRepeat(c, n.parse().unwrap())))
     }
 
     fn parse_alnum(input: &str) -> IResult<&str, Sequence> {
-        tag("[:alnum:]")(input).map(|(l, _)| {
-            (
-                l,
-                Sequence::CharRange(Box::new(('0'..='9').chain('A'..='Z').chain('a'..='z'))),
-            )
-        })
+        tag("[:alnum:]")(input).map(|(l, _)| (l, Sequence::Alnum))
     }
 
     fn parse_alpha(input: &str) -> IResult<&str, Sequence> {
-        tag("[:alpha:]")(input).map(|(l, _)| {
-            (
-                l,
-                Sequence::CharRange(Box::new(('A'..='Z').chain('a'..='z'))),
-            )
-        })
+        tag("[:alpha:]")(input).map(|(l, _)| (l, Sequence::Alpha))
     }
 
     fn parse_blank(input: &str) -> IResult<&str, Sequence> {
-        tag("[:blank:]")(input).map(|(l, _)| {
-            (
-                l,
-                Sequence::CharRange(Box::new(unicode_table::BLANK.into_iter().cloned())),
-            )
-        })
+        tag("[:blank:]")(input).map(|(l, _)| (l, Sequence::Blank))
     }
 
     fn parse_control(input: &str) -> IResult<&str, Sequence> {
-        tag("[:cntrl:]")(input).map(|(l, _)| {
-            (
-                l,
-                Sequence::CharRange(Box::new(
-                    (0..=31)
-                        .chain(std::iter::once(127))
-                        .flat_map(char::from_u32),
-                )),
-            )
-        })
+        tag("[:cntrl:]")(input).map(|(l, _)| (l, Sequence::Control))
     }
 
     fn parse_digit(input: &str) -> IResult<&str, Sequence> {
-        tag("[:digit:]")(input).map(|(l, _)| (l, Sequence::CharRange(Box::new('0'..='9'))))
+        tag("[:digit:]")(input).map(|(l, _)| (l, Sequence::Digit))
     }
 
     fn parse_graph(input: &str) -> IResult<&str, Sequence> {
-        tag("[:graph:]")(input).map(|(l, _)| {
-            (
-                l,
-                Sequence::CharRange(Box::new(
-                    (48..=57) // digit
-                        .chain(65..=90) // uppercase
-                        .chain(97..=122) // lowercase
-                        // punctuations
-                        .chain(33..=47)
-                        .chain(58..=64)
-                        .chain(91..=96)
-                        .chain(123..=126)
-                        .chain(std::iter::once(32)) // space
-                        .flat_map(char::from_u32),
-                )),
-            )
-        })
+        tag("[:graph:]")(input).map(|(l, _)| (l, Sequence::Graph))
     }
 
     fn parse_lower(input: &str) -> IResult<&str, Sequence> {
-        tag("[:lower:]")(input).map(|(l, _)| (l, Sequence::CharRange(Box::new('a'..='z'))))
+        tag("[:lower:]")(input).map(|(l, _)| (l, Sequence::Lower))
     }
 
     fn parse_print(input: &str) -> IResult<&str, Sequence> {
-        tag("[:print:]")(input).map(|(l, _)| {
-            (
-                l,
-                Sequence::CharRange(Box::new(
-                    (48..=57) // digit
-                        .chain(65..=90) // uppercase
-                        .chain(97..=122) // lowercase
-                        // punctuations
-                        .chain(33..=47)
-                        .chain(58..=64)
-                        .chain(91..=96)
-                        .chain(123..=126)
-                        .flat_map(char::from_u32),
-                )),
-            )
-        })
+        tag("[:print:]")(input).map(|(l, _)| (l, Sequence::Print))
     }
 
     fn parse_punct(input: &str) -> IResult<&str, Sequence> {
-        tag("[:punct:]")(input).map(|(l, _)| {
-            (
-                l,
-                Sequence::CharRange(Box::new(
-                    (33..=47)
-                        .chain(58..=64)
-                        .chain(91..=96)
-                        .chain(123..=126)
-                        .flat_map(char::from_u32),
-                )),
-            )
-        })
+        tag("[:punct:]")(input).map(|(l, _)| (l, Sequence::Punct))
     }
 
     fn parse_space(input: &str) -> IResult<&str, Sequence> {
-        tag("[:space:]")(input).map(|(l, _)| {
-            (
-                l,
-                Sequence::CharRange(Box::new(unicode_table::SPACES.into_iter().cloned())),
-            )
-        })
+        tag("[:space:]")(input).map(|(l, _)| (l, Sequence::Space))
     }
 
     fn parse_upper(input: &str) -> IResult<&str, Sequence> {
-        tag("[:upper:]")(input).map(|(l, _)| (l, Sequence::CharRange(Box::new('A'..='Z'))))
+        tag("[:upper:]")(input).map(|(l, _)| (l, Sequence::Upper))
     }
 
     fn parse_xdigit(input: &str) -> IResult<&str, Sequence> {
-        tag("[:xdigit:]")(input).map(|(l, _)| {
-            (
-                l,
-                Sequence::CharRange(Box::new(('0'..='9').chain('A'..='F').chain('a'..='f'))),
-            )
-        })
+        tag("[:xdigit:]")(input).map(|(l, _)| (l, Sequence::Xdigit))
     }
 
     fn parse_char_equal(input: &str) -> IResult<&str, Sequence> {
@@ -339,10 +370,7 @@ pub struct DeleteOperation {
 impl DeleteOperation {
     pub fn new(set: Vec<Sequence>, complement_flag: bool) -> DeleteOperation {
         DeleteOperation {
-            set: set
-                .into_iter()
-                .flat_map(Sequence::dissolve)
-                .collect::<Vec<_>>(),
+            set: set.iter().flat_map(Sequence::flatten).collect::<Vec<_>>(),
             complement_flag,
         }
     }
@@ -355,21 +383,30 @@ impl SymbolTranslator for DeleteOperation {
     }
 }
 
-#[derive(Debug)]
 pub struct TranslateOperationComplement {
     iter: u32,
     set1: Vec<char>,
-    set2: Vec<char>,
+    set2: Box<dyn Iterator<Item = char>>,
     fallback: char,
     translation_map: HashMap<char, char>,
 }
 
 impl TranslateOperationComplement {
-    fn new(set1: Vec<char>, set2: Vec<char>, fallback: char) -> TranslateOperationComplement {
+    fn new(
+        set1: Vec<Sequence>,
+        set2: Vec<Sequence>,
+        set1_truncate_length: Option<usize>,
+        fallback: char,
+    ) -> TranslateOperationComplement {
         TranslateOperationComplement {
             iter: 0,
-            set1,
-            set2: set2.into_iter().rev().collect(),
+            set1: set1
+                .iter()
+                .flat_map(Sequence::flatten)
+                .enumerate()
+                .filter_map(truncate_iterator(set1_truncate_length))
+                .collect(),
+            set2: Box::new(set2.into_iter().flat_map(|c| Sequence::flatten(&c))),
             fallback,
             translation_map: HashMap::new(),
         }
@@ -382,61 +419,83 @@ pub struct TranslateOperationStandard {
 }
 
 impl TranslateOperationStandard {
-    fn new(set1: Vec<char>, set2: Vec<char>, fallback: char) -> TranslateOperationStandard {
+    fn new(
+        set1: Vec<Sequence>,
+        set2: Vec<Sequence>,
+        set1_truncate_length: Option<usize>,
+        fallback: char,
+    ) -> TranslateOperationStandard {
         TranslateOperationStandard {
             translation_map: set1
-                .into_iter()
-                .zip(set2.into_iter().chain(std::iter::repeat(fallback)))
+                .iter()
+                .flat_map(Sequence::flatten)
+                .zip(
+                    set2.iter()
+                        .flat_map(Sequence::flatten)
+                        .chain(Repeat(fallback)),
+                )
+                .enumerate()
+                .filter_map(truncate_iterator(set1_truncate_length))
                 .collect::<HashMap<_, _>>(),
         }
     }
 }
 
-#[derive(Debug)]
 pub enum TranslateOperation {
     Standard(TranslateOperationStandard),
     Complement(TranslateOperationComplement),
 }
 
 impl TranslateOperation {
-    fn next_complement_char(mut iter: u32, ignore_list: &[char]) -> (u32, char) {
-        while (char::from_u32(iter).is_none()
-            || ignore_list
-                .iter()
-                .map(|c| u32::from(*c))
-                .any(|c| iter.eq(&c)))
-            && iter.ne(&u32::MAX)
-        {
-            iter = iter.saturating_add(1)
-        }
-        (iter.saturating_add(1), char::from_u32(iter).unwrap())
+    fn next_complement_char(iter: u32, ignore_list: &[char]) -> (u32, char) {
+        (iter..)
+            .filter_map(char::from_u32)
+            .filter(|c| !ignore_list.iter().any(|s| s.eq(c)))
+            .map(|c| (u32::from(c) + 1, c))
+            .next()
+            .expect("exhausted all possible characters")
     }
 }
 
 impl TranslateOperation {
     pub fn new(
-        pset1: Vec<Sequence>,
-        pset2: Vec<Sequence>,
+        set1: Vec<Sequence>,
+        set2: Vec<Sequence>,
         truncate_set1: bool,
         complement: bool,
     ) -> TranslateOperation {
-        // TODO: Only some translation is acceptable i.e. uppercase/lowercase transform.
-        let mut set1 = pset1
-            .into_iter()
-            .flat_map(Sequence::dissolve)
-            .collect::<Vec<_>>();
-        let set2 = pset2
-            .into_iter()
-            .flat_map(Sequence::dissolve)
-            .collect::<Vec<_>>();
-        let fallback = set2.last().cloned().unwrap();
-        if truncate_set1 {
-            set1.truncate(set2.len());
-        }
-        if complement {
-            TranslateOperation::Complement(TranslateOperationComplement::new(set1, set2, fallback))
+        let fallback = set2
+            .iter()
+            .rev()
+            .next()
+            .map(Sequence::last)
+            .flatten()
+            .unwrap();
+        let set1_truncate_length = if truncate_set1 {
+            set2.iter()
+                .map(Sequence::len)
+                .reduce(|a, b| match (a, b) {
+                    (Some(l), Some(r)) => Some(l + r),
+                    _ => None,
+                })
+                .flatten()
         } else {
-            TranslateOperation::Standard(TranslateOperationStandard::new(set1, set2, fallback))
+            None
+        };
+        if complement {
+            TranslateOperation::Complement(TranslateOperationComplement::new(
+                set1,
+                set2,
+                set1_truncate_length,
+                fallback,
+            ))
+        } else {
+            TranslateOperation::Standard(TranslateOperationStandard::new(
+                set1,
+                set2,
+                set1_truncate_length,
+                fallback,
+            ))
         }
     }
 }
@@ -466,7 +525,7 @@ impl SymbolTranslator for TranslateOperation {
                     Some(*c)
                 } else {
                     while translation_map.get(&current).is_none() {
-                        if let Some(p) = set2.pop() {
+                        if let Some(p) = set2.next() {
                             let (next_index, next_value) =
                                 TranslateOperation::next_complement_char(*iter, &*set1);
                             *iter = next_index;
@@ -484,18 +543,15 @@ impl SymbolTranslator for TranslateOperation {
 
 #[derive(Debug, Clone)]
 pub struct SqueezeOperation {
-    squeeze_set: Vec<char>,
+    set1: Vec<char>,
     complement: bool,
     previous: Option<char>,
 }
 
 impl SqueezeOperation {
-    pub fn new(squeeze_set: Vec<Sequence>, complement: bool) -> SqueezeOperation {
+    pub fn new(set1: Vec<Sequence>, complement: bool) -> SqueezeOperation {
         SqueezeOperation {
-            squeeze_set: squeeze_set
-                .into_iter()
-                .flat_map(Sequence::dissolve)
-                .collect(),
+            set1: set1.iter().flat_map(Sequence::flatten).collect(),
             complement,
             previous: None,
         }
@@ -505,7 +561,7 @@ impl SqueezeOperation {
 impl SymbolTranslator for SqueezeOperation {
     fn translate(&mut self, current: char) -> Option<char> {
         if self.complement {
-            let next = if self.squeeze_set.iter().any(|c| c.eq(&current)) {
+            let next = if self.set1.iter().any(|c| c.eq(&current)) {
                 Some(current)
             } else {
                 match self.previous {
@@ -526,7 +582,7 @@ impl SymbolTranslator for SqueezeOperation {
             self.previous = Some(current);
             next
         } else {
-            let next = if self.squeeze_set.iter().any(|c| c.eq(&current)) {
+            let next = if self.set1.iter().any(|c| c.eq(&current)) {
                 match self.previous {
                     Some(v) if v == current => None,
                     _ => Some(current),
@@ -542,7 +598,7 @@ impl SymbolTranslator for SqueezeOperation {
 
 pub fn translate_input<T, R, W>(input: &mut R, output: &mut W, mut translator: T)
 where
-    T: SymbolTranslator + Debug,
+    T: SymbolTranslator,
     R: BufRead,
     W: Write,
 {