From cd725638cd29b3e2ba9ef8f2d20de7f34ca6663d Mon Sep 17 00:00:00 2001
From: Dave Holoway <adelphes@gmail.com>
Date: Wed, 10 Jun 2020 18:43:43 +0100
Subject: [PATCH] parse labels and break/continue targets

---
 langserver/java/TokenList.js    | 18 +++++++++++++++
 langserver/java/body-parser3.js | 39 ++++++++++++++++++++++++++++++---
 2 files changed, 54 insertions(+), 3 deletions(-)

diff --git a/langserver/java/TokenList.js b/langserver/java/TokenList.js
index 342a206..7389060 100644
--- a/langserver/java/TokenList.js
+++ b/langserver/java/TokenList.js
@@ -25,6 +25,24 @@ class TokenList {
             }
         }
     }
+
+    /**
+     * Token lookahead. The current token is unaffected by this method.
+     * @param {number} n number of tokens to look ahead
+     */
+    peek(n) {
+        let token, idx = this.idx;
+        while (--n >= 0) {
+            for (; ;) {
+                token = this.tokens[idx += 1];
+                if (!token || token.kind !== 'wsc') {
+                    break;
+                }
+            }
+        }
+        return token;
+    }
+
     /**
      * Check if the current token matches the specified value and consumes it
      * @param {string} value
diff --git a/langserver/java/body-parser3.js b/langserver/java/body-parser3.js
index 7fd91c5..3153f35 100644
--- a/langserver/java/body-parser3.js
+++ b/langserver/java/body-parser3.js
@@ -99,8 +99,19 @@ function statement(tokens, locals, method, imports, typemap) {
         case 'statement-kw':
             s = statementKeyword(tokens, locals, method, imports, typemap);
             return s;
-        case 'modifier':
         case 'ident':
+            // checking every statement identifier for a possible label is really inefficient, but trying to
+            // merge this into expression_or_var_decl is worse for now
+            if (tokens.peek(1).value === ':') {
+                const label = new Label(tokens.current);
+                tokens.inc(), tokens.inc();
+                // ignore and just return the next statement
+                // - we cannot return the label as a statement because for/if/while check the next statement type
+                // the labels should be collated and checked for duplicates, etc
+                return statement(tokens, locals, method, imports, typemap);
+            }
+            // fall-through to expression_or_var_decl
+        case 'modifier':
         case 'primitive-type':
             s = expression_or_var_decl(tokens, locals, method, imports, typemap);
             if (Array.isArray(s)) {
@@ -158,8 +169,14 @@ class WhileStatement extends Statement {
     test = null;
     statement = null;
 }
-class BreakStatement extends Statement {}
-class ContinueStatement extends Statement {}
+class BreakStatement extends Statement {
+    /** @type {Token} */
+    target = null;
+}
+class ContinueStatement extends Statement {
+    /** @type {Token} */
+    target = null;
+}
 class DoStatement extends Statement {
     test = null;
     block = null;
@@ -193,6 +210,14 @@ class AssertStatement extends Statement {
     expression = null;
     message = null;
 }
+class Label {
+    /**
+     * @param {Token} token 
+     */
+    constructor(token) {
+        this.name_token = token;
+    }
+}
 
 /**
  * @param {TokenList} tokens 
@@ -253,11 +278,19 @@ function statementKeyword(tokens, locals, method, imports, typemap) {
         case 'break':
             tokens.inc();
             s = new BreakStatement();
+            if (tokens.current.kind === 'ident') {
+                s.target = tokens.current;
+                tokens.inc();
+            }
             semicolon(tokens);
             break;
         case 'continue':
             tokens.inc();
             s = new ContinueStatement();
+            if (tokens.current.kind === 'ident') {
+                s.target = tokens.current;
+                tokens.inc();
+            }
             semicolon(tokens);
             break;
         case 'switch':