Feat: Create dedicated parser module for grammar

src/parser.js

@@ -0,0 +1,108 @@
+import { CstParser } from 'chevrotain';
+import {
+    allTokens,
+    Identifier, Number, String,
+    LBrace, RBrace, LParen, RParen,
+    Dot, Plus, Comma, Colon, Eq
+} from './lexer.js';
+
+class HiParser extends CstParser {
+    constructor() {
+        super(allTokens);
+
+        const $ = this;
+
+        $.RULE('program', () => $.SUBRULE($.statements));
+        $.RULE('statements', () => $.MANY(() => $.SUBRULE($.statement)));
+
+        $.RULE('statement', () => {
+            $.OR([
+                { ALT: () => $.SUBRULE($.declaration) },
+                { ALT: () => $.SUBRULE($.assignment) },
+                { ALT: () => $.SUBRULE($.expressionStatement) },
+            ]);
+        });
+        
+        $.RULE('expressionStatement', () => $.SUBRULE($.expression));
+
+        $.RULE('declaration', () => {
+            $.CONSUME(Identifier);
+            $.CONSUME(Colon);
+            $.SUBRULE($.expression);
+        });
+
+        $.RULE('assignment', () => {
+            $.CONSUME(Identifier);
+            $.CONSUME(Eq);
+            $.SUBRULE($.expression);
+        });
+
+        $.RULE('expression', () => $.SUBRULE($.additiveExpression));
+
+        $.RULE('additiveExpression', () => {
+            $.SUBRULE($.callExpression, { LABEL: 'left' });
+            $.MANY(() => {
+                $.CONSUME(Plus);
+                $.SUBRULE2($.callExpression, { LABEL: 'right' });
+            });
+        });
+
+        $.RULE('callExpression', () => {
+            $.SUBRULE($.memberExpression);
+            $.OPTION(() => {
+                $.CONSUME(LParen);
+                $.OPTION2(() => $.SUBRULE($.argumentList));
+                $.CONSUME(RParen);
+            });
+        });
+
+        $.RULE('argumentList', () => {
+            $.SUBRULE($.expression);
+            $.MANY(() => {
+                $.CONSUME(Comma);
+                $.SUBRULE2($.expression);
+            });
+        });
+
+        $.RULE('memberExpression', () => {
+            $.SUBRULE($.primary);
+            $.MANY(() => {
+                $.CONSUME(Dot);
+                $.CONSUME(Identifier);
+            });
+        });
+
+        $.RULE('primary', () => {
+            $.OR([
+                { ALT: () => $.SUBRULE($.literal) },
+                { ALT: () => $.CONSUME(Identifier) },
+                { ALT: () => $.SUBRULE($.block) },
+                { ALT: () => {
+                    $.CONSUME(LParen);
+                    $.SUBRULE($.expression);
+                    $.CONSUME(RParen);
+                }}
+            ]);
+        });
+
+        $.RULE('literal', () => $.OR([{ ALT: () => $.CONSUME(Number) }, { ALT: () => $.CONSUME(String) }]));
+
+        $.RULE('block', () => {
+            $.CONSUME(LBrace);
+            $.OPTION(() => $.SUBRULE($.keyValuePairs));
+            $.CONSUME(RBrace);
+        });
+        
+        $.RULE('keyValuePairs', () => $.AT_LEAST_ONE(() => $.SUBRULE($.keyValuePair)));
+
+        $.RULE('keyValuePair', () => {
+            $.CONSUME(Identifier);
+            $.CONSUME(Colon);
+            $.SUBRULE($.expression);
+        });
+        
+        this.performSelfAnalysis();
+    }
+}
+
+export const parser = new HiParser();