Add bytes.center

fix str.center
add some tests
introduce is_byte

Author: jgirardet

tests/snippets/bytes.py

@@ -131,3 +131,30 @@
 except ValueError as e:
     str(e) == "non-hexadecimal number found in fromhex() arg at position 1"
 
+# center
+assert [b"koki".center(i, b"|") for i in range(3, 10)] == [
+    b"koki",
+    b"koki",
+    b"|koki",
+    b"|koki|",
+    b"||koki|",
+    b"||koki||",
+    b"|||koki||",
+]
+
+assert [b"kok".center(i, b"|") for i in range(2, 10)] == [
+    b"kok",
+    b"kok",
+    b"kok|",
+    b"|kok|",
+    b"|kok||",
+    b"||kok||",
+    b"||kok|||",
+    b"|||kok|||",
+]
+b"kok".center(4) == b" kok"  # " test no arg"
+with assertRaises(TypeError):
+    b"b".center(2, "a")
+with assertRaises(TypeError):
+    b"b".center(2, b"ba")
+b"kok".center(5, bytearray(b"x"))

tests/snippets/strings.py

@@ -55,6 +55,29 @@
 c = 'hallo'
 assert c.capitalize() == 'Hallo'
 assert c.center(11, '-') == '---hallo---'
+assert ["koki".center(i, "|") for i in range(3, 10)] == [
+    "koki",
+    "koki",
+    "|koki",
+    "|koki|",
+    "||koki|",
+    "||koki||",
+    "|||koki||",
+]
+
+
+assert ["kok".center(i, "|") for i in range(2, 10)] == [
+    "kok",
+    "kok",
+    "kok|",
+    "|kok|",
+    "|kok||",
+    "||kok||",
+    "||kok|||",
+    "|||kok|||",
+]
+
+
 # assert c.isascii()
 assert c.index('a') == 1
 assert c.rindex('l') == 3

vm/src/obj/objbyteinner.rs

@@ -1,4 +1,5 @@
 use crate::pyobject::PyObjectRef;
+use num_bigint::BigInt;
 
 use crate::function::OptionalArg;
 
@@ -13,8 +14,12 @@ use std::hash::{Hash, Hasher};
 use super::objint;
 use super::objsequence::PySliceableSequence;
 use crate::obj::objint::PyInt;
+use num_integer::Integer;
 use num_traits::ToPrimitive;
 
+use super::objbytearray::{get_value as get_value_bytearray, PyByteArray};
+use super::objbytes::PyBytes;
+
 #[derive(Debug, Default, Clone)]
 pub struct PyByteInner {
     pub elements: Vec<u8>,
@@ -355,4 +360,39 @@ impl PyByteInner {
             .map(|x| x.unwrap())
             .collect::<Vec<u8>>())
     }
+
+    pub fn center(&self, width: &BigInt, fillbyte: u8, _vm: &VirtualMachine) -> Vec<u8> {
+        let width = width.to_usize().unwrap();
+
+        // adjust right et left side
+        if width <= self.len() {
+            return self.elements.clone();
+        }
+        let diff: usize = width - self.len();
+        let mut ln: usize = diff / 2;
+        let mut rn: usize = ln;
+
+        if diff.is_odd() && self.len() % 2 == 0 {
+            ln += 1
+        }
+
+        if diff.is_odd() && self.len() % 2 != 0 {
+            rn += 1
+        }
+
+        // merge all
+        let mut res = vec![fillbyte; ln];
+        res.extend_from_slice(&self.elements[..]);
+        res.extend_from_slice(&vec![fillbyte; rn][..]);
+
+        res
+    }
+}
+
+pub fn is_byte(obj: &PyObjectRef) -> Option<Vec<u8>> {
+    match_class!(obj.clone(),
+
+    i @ PyBytes => Some(i.get_value().to_vec()),
+    j @ PyByteArray => Some(get_value_bytearray(&j.as_object()).to_vec()),
+    _ => None)
 }

vm/src/obj/objbytes.rs

@@ -7,7 +7,7 @@ use std::ops::Deref;
 use crate::function::OptionalArg;
 use crate::pyobject::{PyClassImpl, PyContext, PyObjectRef, PyRef, PyResult, PyValue};
 
-use super::objbyteinner::PyByteInner;
+use super::objbyteinner::{is_byte, PyByteInner};
 use super::objiter;
 use super::objslice::PySlice;
 use super::objtype::PyClassRef;
@@ -34,6 +34,10 @@ impl PyBytes {
             inner: PyByteInner { elements },
         }
     }
+
+    pub fn get_value(&self) -> &[u8] {
+        &self.inner.elements
+    }
 }
 
 impl Deref for PyBytes {
@@ -229,6 +233,42 @@ impl PyBytesRef {
         obj => Err(vm.new_type_error(format!("fromhex() argument must be str, not {}", obj )))
         )
     }
+
+    #[pymethod(name = "center")]
+    fn center(
+        self,
+        width: PyObjectRef,
+        fillbyte: OptionalArg<PyObjectRef>,
+        vm: &VirtualMachine,
+    ) -> PyResult {
+        let sym = if let OptionalArg::Present(v) = fillbyte {
+            match is_byte(&v) {
+                Some(x) => {
+                    if x.len() == 1 {
+                        x[0]
+                    } else {
+                        return Err(vm.new_type_error(format!(
+                            "center() argument 2 must be a byte string of length 1, not {}",
+                            &v
+                        )));
+                    }
+                }
+                None => {
+                    return Err(vm.new_type_error(format!(
+                        "center() argument 2 must be a byte string of length 1, not {}",
+                        &v
+                    )));
+                }
+            }
+        } else {
+            32 // default is space
+        };
+
+        match_class!(width,
+        i @PyInt => Ok(vm.ctx.new_bytes(self.inner.center(i.as_bigint(), sym, vm))),
+        obj => {Err(vm.new_type_error(format!("{} cannot be interpreted as an integer", obj)))}
+        )
+    }
 }
 
 #[derive(Debug)]

vm/src/obj/objstr.rs

@@ -691,8 +691,22 @@ impl PyStringRef {
     ) -> PyResult<String> {
         let value = &self.value;
         let rep_char = Self::get_fill_char(&rep, vm)?;
-        let left_buff: usize = (len - value.len()) / 2;
-        let right_buff = len - value.len() - left_buff;
+        let value_len = self.value.chars().count();
+
+        if len <= value_len {
+            return Ok(value.to_string());
+        }
+        let diff: usize = len - value_len;
+        let mut left_buff: usize = diff / 2;
+        let mut right_buff: usize = left_buff;
+
+        if diff % 2 != 0 && value_len % 2 == 0 {
+            left_buff += 1
+        }
+
+        if diff % 2 != 0 && value_len % 2 != 0 {
+            right_buff += 1
+        }
         Ok(format!(
             "{}{}{}",
             rep_char.repeat(left_buff),