parser: preserve scope data as metadata

1 files changed, 63 insertions, 14 deletions

diff --git a/src/parser.rs b/src/parser.rs
index 69c4856..544c296 100644
--- a/src/parser.rs
+++ b/src/parser.rs
@@ -1,5 +1,7 @@
 use crate::tokenizer::{self, If, Keyword::*, Loop};
 
+pub type SplitWithMetadata<'a> = Vec<(&'a str, Option<Metadata>)>;
+
 pub const EXPRESSION_DELIMITERS: &[char] = &[
     ';', '{', '}',
 ];
@@ -11,40 +13,87 @@ pub enum Scope {
 }
 
 #[derive(Debug)]
-pub enum Expr<'a> {
+pub enum Metadata {
+    StartScope,
+    EndScope,
+}
+
+#[derive(Debug)]
+pub enum ExprT<'a> {
     StartOrStop(bool),
     Decision((&'a str, Scope)),
     IO(&'a str),
     Process(&'a str),
 }
 
-pub fn delimit(str: &str) -> Vec<&str> {
-    str.split(|c| EXPRESSION_DELIMITERS.contains(&c))
-        .filter(|c| !c.is_empty())
-        .collect()
+#[derive(Debug)]
+pub struct Expr<'a> {
+    pub expr: ExprT<'a>,
+    pub meta: Option<Metadata>,
+}
+
+pub fn delimit(s: &str) -> SplitWithMetadata<'_> {
+    s.split_inclusive([
+        ';', '{', '}',
+    ])
+    .fold(Vec::new(), |mut acc, part| {
+        if let Some((i, ch)) = part
+            .char_indices()
+            .next_back()
+        {
+            let body = if ch == ';' || ch == '{' || ch == '}' {
+                part[..i].trim()
+            } else {
+                part.trim()
+            };
+            if !body.is_empty() {
+                acc.push((body, None));
+            }
+            match ch {
+                '{' => {
+                    if let Some(last) = acc.last_mut() {
+                        last.1 = Some(Metadata::StartScope);
+                    }
+                }
+                '}' => {
+                    if let Some(last) = acc.last_mut() {
+                        last.1 = Some(Metadata::EndScope);
+                    }
+                }
+                _ => {}
+            }
+        }
+        acc
+    })
 }
 
-pub fn process(strs: Vec<&str>) -> Vec<Expr<'_>> {
+pub fn process(strs: SplitWithMetadata<'_>) -> Vec<Expr<'_>> {
     let mut exprs = Vec::new();
 
-    for str in strs {
-        let mut exp: Option<Expr> = None;
+    for (str, meta) in strs {
+        let mut exp: Option<ExprT> = None;
 
         // TODO: fix one line if else as not delimited by {}
         for s in str.split_whitespace() {
             if let Some(token) = tokenizer::parse(s) {
                 exp = match token {
-                    If(t) => Some(Expr::Decision((str, Scope::If(t.to_owned())))),
-                    Loop(t) => Some(Expr::Decision((str, Scope::Loop(t.to_owned())))),
-                    Throw => Some(Expr::IO(str)),
-                    IO => Some(Expr::IO(str)),
+                    If(t) => Some(ExprT::Decision((str, Scope::If(t.to_owned())))),
+                    Loop(t) => Some(ExprT::Decision((str, Scope::Loop(t.to_owned())))),
+                    Throw => Some(ExprT::IO(str)),
+                    IO => Some(ExprT::IO(str)),
                 }
             }
         }
 
         match exp {
-            Some(exp) => exprs.push(exp),
-            None => exprs.push(Expr::Process(str)),
+            Some(expr) => exprs.push(Expr {
+                expr,
+                meta,
+            }),
+            None => exprs.push(Expr {
+                expr: ExprT::Process(str),
+                meta: None,
+            }),
         }
     }