feat(text): add FromIterator impls for Line and Text (#967)

This adds `FromIterator` impls for `Line` and `Text` that allow creating
`Line` and `Text` instances from iterators of `Span` and `Line`
instances, respectively.

```rust
let line = Line::from_iter(vec!["Hello".blue(), " world!".green()]);
let line: Line = iter::once("Hello".blue())
    .chain(iter::once(" world!".green()))
    .collect();
let text = Text::from_iter(vec!["The first line", "The second line"]);
let text: Text = iter::once("The first line")
    .chain(iter::once("The second line"))
    .collect();
```

src/text/line.rs

@@ -2,7 +2,7 @@
 use std::borrow::Cow;
 
 use super::StyledGrapheme;
-use crate::{prelude::*, widgets::Widget};
+use crate::prelude::*;
 
 /// A line of text, consisting of one or more [`Span`]s.
 ///
@@ -443,6 +443,15 @@ impl<'a> From<Line<'a>> for String {
     }
 }
 
+impl<'a, T> FromIterator<T> for Line<'a>
+where
+    T: Into<Span<'a>>,
+{
+    fn from_iter<I: IntoIterator<Item = T>>(iter: I) -> Self {
+        Self::from(iter.into_iter().map(Into::into).collect::<Vec<_>>())
+    }
+}
+
 impl Widget for Line<'_> {
     fn render(self, area: Rect, buf: &mut Buffer) {
         self.render_ref(area, buf);
@@ -488,6 +497,8 @@ impl std::fmt::Display for Line<'_> {
 
 #[cfg(test)]
 mod tests {
+    use std::iter;
+
     use rstest::{fixture, rstest};
 
     use super::*;
@@ -625,6 +636,32 @@ mod tests {
         assert_eq!(spans, line.spans);
     }
 
+    #[test]
+    fn from_iter() {
+        let line = Line::from_iter(vec!["Hello".blue(), " world!".green()]);
+        assert_eq!(
+            line.spans,
+            vec![
+                Span::styled("Hello", Style::new().blue()),
+                Span::styled(" world!", Style::new().green()),
+            ]
+        );
+    }
+
+    #[test]
+    fn collect() {
+        let line: Line = iter::once("Hello".blue())
+            .chain(iter::once(" world!".green()))
+            .collect();
+        assert_eq!(
+            line.spans,
+            vec![
+                Span::styled("Hello", Style::new().blue()),
+                Span::styled(" world!", Style::new().green()),
+            ]
+        );
+    }
+
     #[test]
     fn from_span() {
         let span = Span::styled("Hello, world!", Style::default().fg(Color::Yellow));

src/text/span.rs

@@ -4,7 +4,7 @@ use unicode_segmentation::UnicodeSegmentation;
 use unicode_width::UnicodeWidthStr;
 
 use super::StyledGrapheme;
-use crate::{prelude::*, widgets::Widget};
+use crate::prelude::*;
 
 /// Represents a part of a line that is contiguous and where all characters share the same style.
 ///

src/text/text.rs

@@ -419,6 +419,19 @@ impl<'a> From<Vec<Line<'a>>> for Text<'a> {
     }
 }
 
+impl<'a, T> FromIterator<T> for Text<'a>
+where
+    T: Into<Line<'a>>,
+{
+    fn from_iter<I: IntoIterator<Item = T>>(iter: I) -> Self {
+        let lines = iter.into_iter().map(Into::into).collect();
+        Text {
+            lines,
+            ..Default::default()
+        }
+    }
+}
+
 impl<'a, T> Extend<T> for Text<'a>
 where
     T: Into<Line<'a>>,
@@ -486,6 +499,8 @@ impl<'a> Styled for Text<'a> {
 
 #[cfg(test)]
 mod tests {
+    use std::iter;
+
     use rstest::{fixture, rstest};
 
     use super::*;
@@ -601,6 +616,26 @@ mod tests {
         );
     }
 
+    #[test]
+    fn from_iterator() {
+        let text = Text::from_iter(vec!["The first line", "The second line"]);
+        assert_eq!(
+            text.lines,
+            vec![Line::from("The first line"), Line::from("The second line")]
+        );
+    }
+
+    #[test]
+    fn collect() {
+        let text: Text = iter::once("The first line")
+            .chain(iter::once("The second line"))
+            .collect();
+        assert_eq!(
+            text.lines,
+            vec![Line::from("The first line"), Line::from("The second line")]
+        );
+    }
+
     #[test]
     fn into_iter() {
         let text = Text::from("The first line\nThe second line");