Add decorator

src/helpers/mod.rs

@@ -1,4 +1,6 @@
 use std::path::PathBuf;
+use pest::iterators::{Pair, Pairs};
+use crate::parser::Rule;
 
 pub const FILE_EXTENSION: &str = "mg";
 
@@ -14,4 +16,72 @@ pub(crate) fn expand_tilde(path: PathBuf) -> color_eyre::Result<PathBuf> {
         return Ok(home.join(relative));
     }
     Ok(path)
+}
+
+pub(crate) fn expand_next_rule(mut rule: Pairs<Rule>) -> Option<Pairs<Rule>> {
+    if let Some(inner) = rule.next() {
+        Some(inner.into_inner())
+    } else { None }
+}
+
+pub(crate) fn unbox_string(string: Pair<Rule>) -> String {
+    let str = string.as_str();
+    str[1..str.len()-1].to_string()
+}
+
+pub(crate) fn format_pair(pair: Pair<Rule>, indent_level: usize, is_newline: bool) -> String {
+    let indent = if is_newline {
+        "  ".repeat(indent_level)
+    } else {
+        String::new()
+    };
+
+    let children: Vec<_> = pair.clone().into_inner().collect();
+    let len = children.len();
+    let children: Vec<_> = children
+        .into_iter()
+        .map(|pair| {
+            format_pair(
+                pair,
+                if len > 1 {
+                    indent_level + 1
+                } else {
+                    indent_level
+                },
+                len > 1,
+            )
+        })
+        .collect();
+
+    let dash = if is_newline { "- " } else { "" };
+    let pair_tag = match pair.as_node_tag() {
+        Some(tag) => format!("(#{}) ", tag),
+        None => String::new(),
+    };
+    match len {
+        0 => format!(
+            "{}{}{}{:?}: {:?}",
+            indent,
+            dash,
+            pair_tag,
+            pair.as_rule(),
+            pair.as_span().as_str()
+        ),
+        1 => format!(
+            "{}{}{}{:?} > {}",
+            indent,
+            dash,
+            pair_tag,
+            pair.as_rule(),
+            children[0]
+        ),
+        _ => format!(
+            "{}{}{}{:?}\n{}",
+            indent,
+            dash,
+            pair_tag,
+            pair.as_rule(),
+            children.join("\n")
+        ),
+    }
 }