Wrote plain text parser.

src/parser/object.rs

@@ -1,6 +1,11 @@
+use nom::combinator::map;
 use nom::combinator::not;
 
+use crate::parser::error::CustomError;
+use crate::parser::error::MyError;
+
 use super::error::Res;
+use super::parser_with_context::parser_with_context;
 use super::source::Source;
 use super::Context;
 
@@ -41,5 +46,43 @@ pub fn standard_set_object<'r, 's>(
     input: &'s str,
 ) -> Res<&'s str, Object<'s>> {
     not(|i| context.check_exit_matcher(i))(input)?;
-    todo!()
+
+    let plain_text_matcher = parser_with_context!(plain_text)(context);
+
+    map(plain_text_matcher, Object::PlainText)(input)
+}
+
+fn plain_text<'r, 's>(context: Context<'r, 's>, input: &'s str) -> Res<&'s str, PlainText<'s>> {
+    if input.len() == 0 {
+        return Err(nom::Err::Error(CustomError::MyError(MyError(
+            "Zero input length to plain_text.",
+        ))));
+    }
+    // not(|i| context.check_exit_matcher(i))(input)?;
+    let mut current_input = input.char_indices();
+    loop {
+        match current_input.next() {
+            Some((offset, _char)) => {
+                let remaining = &input[offset..];
+                let exit_matcher_status = context.check_exit_matcher(remaining);
+                if exit_matcher_status.is_err() {
+                    if offset == 0 {
+                        // If we're at the start of the input, then nothing is plain text, so fire an error for zero-length match.
+                        exit_matcher_status?;
+                    } else {
+                        return Ok((
+                            &input[offset..],
+                            PlainText {
+                                source: &input[..offset],
+                            },
+                        ));
+                    }
+                }
+            }
+            None => {
+                // We hit the end of the file, so all input must be plain text
+                return Ok((&input[input.len()..], PlainText { source: input }));
+            }
+        };
+    }
 }