refactor to prepare for merging with type parsing

langserver/java/TokenList.js

@@ -0,0 +1,72 @@
+/**
+ * @typedef {import('./tokenizer').Token} Token
+ */
+const ParseProblem = require('./parsetypes/parse-problem');
+
+class TokenList {
+    /**
+     * @param {Token[]} tokens
+     */
+    constructor(tokens) {
+        this.tokens = tokens;
+        this.idx = -1;
+        /** @type {Token} */
+        this.current = null;
+        this.inc();
+        /** @type {ParseProblem[]} */
+        this.problems = [];
+    }
+
+    inc() {
+        for (; ;) {
+            this.current = this.tokens[this.idx += 1];
+            if (!this.current || this.current.kind !== 'wsc') {
+                return this.current;
+            }
+        }
+    }
+    /**
+     * Check if the current token matches the specified value and consumes it
+     * @param {string} value
+     */
+    isValue(value) {
+        if (this.current.value === value) {
+            this.inc();
+            return true;
+        }
+        return false;
+    }
+
+    /**
+     * Check if the current token matches the specified value and consumes it or reports an error
+     * @param {string} value
+     */
+    expectValue(value) {
+        if (this.isValue(value)) {
+            return true;
+        }
+        const addproblem = require("./body-parser3").addproblem;
+        addproblem(this, ParseProblem.Error(this.current, `${value} expected`));
+        return false;
+    }
+
+    get previous() {
+        for (let idx = this.idx - 1; idx >= 0; idx--) {
+            if (idx === 0 || this.tokens[idx].kind !== 'wsc') {
+                return this.tokens[idx];
+            }
+        }
+    }
+
+    /**
+     * @param {number} start 
+     * @param {number} delete_count 
+     * @param  {...Token} insert 
+     */
+    splice(start, delete_count, ...insert) {
+        this.tokens.splice(start, delete_count, ...insert);
+        this.current = this.tokens[this.idx];
+    }
+}
+
+exports.TokenList = TokenList;