Add custom validator to fix multiline behaviour when working with strings

src/bin/relish.rs

@@ -42,7 +42,7 @@ use {
         Reedline, Signal, Prompt, PromptEditMode, PromptHistorySearch,
         PromptHistorySearchStatus, Completer, Suggestion, Span,
         KeyModifiers, KeyCode, ReedlineEvent, Keybindings,
-        ColumnarMenu, Emacs, ReedlineMenu,
+        ColumnarMenu, Emacs, ReedlineMenu, Validator, ValidationResult,
         default_emacs_keybindings,
     },
     nu_ansi_term::{Color, Style},
@@ -61,6 +61,8 @@ pub struct CustomPrompt(String, String, String);
 #[derive(Clone)]
 pub struct CustomCompleter(Vec<String>);
 
+pub struct CustomValidator;
+
 impl Prompt for CustomPrompt {
     fn render_prompt_left(&self) -> Cow<str> {
         {
@@ -221,6 +223,51 @@ impl Completer for CustomCompleter {
     }
 }
 
+impl Validator for CustomValidator {
+    fn validate(&self, line: &str) -> ValidationResult {
+        if incomplete_brackets(line) {
+            ValidationResult::Incomplete
+        } else {
+            ValidationResult::Complete
+        }
+    }
+}
+
+fn incomplete_brackets(line: &str) -> bool {
+    let mut balance: Vec<char> = Vec::new();
+    let mut within_string: Option<char> = None;
+
+    for c in line.chars() {
+        match c {
+            c if ['"', '`', '\''].contains(&c) => {
+		match within_string {
+		    Some(w) if c == w => {
+			balance.pop();
+			within_string = None
+		    }
+		    Some(_) => {},
+		    None => {
+			balance.push(c);
+			within_string = Some(c)
+		    },
+		}
+	    },
+
+	    '(' if within_string.is_none() => balance.push(')'),
+
+            ')' => if let Some(last) = balance.last() {
+                if last == &c {
+                    balance.pop();
+                }
+            },
+
+            _ => {}
+        }
+    }
+
+    !balance.is_empty()
+}
+
 fn add_menu_keybindings(keybindings: &mut Keybindings) {
     keybindings.add_binding(
         KeyModifiers::NONE,
@@ -313,7 +360,7 @@ fn main() {
     rl = rl.with_hinter(Box::new(
         DefaultHinter::default()
             .with_style(Style::new().italic().fg(Color::LightGray)),
-    )).with_validator(Box::new(DefaultValidator));
+    )).with_validator(Box::new(CustomValidator));
 
     let mut xdimension: u16 = 0;
     let mut ydimension: u16 = 0;