1 files changed, 62 insertions, 0 deletions
diff --git a/headers/src/header_components/utils/text_partition.rs b/headers/src/header_components/utils/text_partition.rs
new file mode 100644
index 0000000..59047b5
--- /dev/null
+++ b/headers/src/header_components/utils/text_partition.rs
@@ -0,0 +1,62 @@
+use internals::grammar::{is_vchar, is_ws};
+use internals::MailType;
+
+
+#[derive(Copy, Clone, Debug, Fail, PartialEq, Eq, Hash)]
+#[fail(display = "text contained control characters")]
+pub struct PartitionError;
+
+#[derive(Copy, Clone)]
+pub enum Partition<'a> {
+    //from -> to the start of the next block
+    SPACE(&'a str),
+    VCHAR(&'a str)
+}
+
+#[derive(Clone, Copy, PartialEq)]
+enum Type { SPACE, VCHAR }
+
+pub fn partition<'a>( text: &'a str ) -> Result<Vec<Partition<'a>>, PartitionError> {
+    use self::Type::*;
+
+    if text.len() == 0 {
+        return Ok( Vec::new() );
+    }
+
+    // unwrap is ok, as we return earlier if len == 0
+    let start_with_vchar = is_vchar( text.chars().next().unwrap(), MailType::Internationalized);
+
+    let mut partitions =  Vec::new();
+    let mut current_type = if start_with_vchar { VCHAR } else { SPACE };
+
+    let mut start_of_current = 0;
+    for (idx, ch) in text.char_indices() {
+        if is_vchar(ch, MailType::Internationalized) {
+            if current_type == SPACE {
+                // idx is the start index of the current char, with is the
+                // (exclusive) end index of the previous char which is the
+                // last char of the Partition we want to push
+                partitions.push(Partition::SPACE(&text[start_of_current..idx]));
+                start_of_current = idx;
+                current_type = VCHAR
+            }
+        } else if is_ws(ch) || ch == '\r' || ch == '\n' {
+            if current_type == VCHAR {
+                partitions.push(Partition::VCHAR(&text[start_of_current..idx]));
+                start_of_current = idx;
+                current_type = SPACE
+            }
+        } else {
+            //TODO look into this error case and especially PartitionError's Display impl
+            return Err(PartitionError);
+        }
+    }
+
+
+    partitions.push( match current_type {
+        SPACE => Partition::SPACE(&text[start_of_current..]),
+        VCHAR => Partition::VCHAR(&text[start_of_current..])
+    } );
+
+    Ok( partitions )
+}
+\ No newline at end of file