Parser: semicolon statement separation; trailing comma fix

nois-lang · Jun 9, 2023 · 35551fa · 35551fa
1 parent 819321e
commit 35551fa
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Showing 4 changed files with 17 additions and 11 deletions.
diff --git a/nois.bnf b/nois.bnf
@@ -71,7 +71,7 @@ statement           ::= var-def | fn-def | type-def | return-stmt | expr
                     ;
         param       ::= IDENTIFIER type-annot?
                     ;
-block               ::= O-BRACE statement* C-BRACE
+block               ::= O-BRACE (statement (SEMI statement)* SEMI?)? C-BRACE
                     ;
 type-annot          ::= COLON type-expr
                     ;

diff --git a/src/lexer/lexer.ts b/src/lexer/lexer.ts
@@ -21,6 +21,7 @@ export const lexerTokenKinds = <const>[
     'o-angle',
     'c-angle',
     'colon',
+    'semi',
     'comma',
     'equals',
     'underscore',
@@ -90,6 +91,7 @@ export const constTokenKindMap: Map<TokenKind, string> = new Map([
     ['period', '.'],
 
     ['colon', ':'],
+    ['semi', ';'],
     ['comma', ','],
     ['equals', '='],
     ['underscore', '_'],
@@ -98,7 +100,7 @@ export const constTokenKindMap: Map<TokenKind, string> = new Map([
 /**
  * Independent tokens are automatically advanced by parser by default
  */
-export const independentTokenKinds: Set<TokenKind> = new Set(['newline', 'comment'])
+export const independentTokenKinds: TokenKind[] = ['newline', 'comment']
 
 export const isWhitespace = (char: string): boolean => char === ' ' || char === '\t'
 

diff --git a/src/parser/parser.spec.ts b/src/parser/parser.spec.ts
@@ -96,9 +96,10 @@ describe('parser', () => {
         it('mismatch paren', () => {
 
             const { errors } = parse('if a { b) }')
-            expect(errors.length).toEqual(3)
+            // TODO: reduce multiple errors on the same symbol to the last one
+            expect(errors.length).toEqual(2)
             expect(errors[0]).toEqual({
-                'expected': ['c-brace'],
+                'expected': ['semi'],
                 'got': { 'kind': 'c-paren', 'location': { 'end': 8, 'start': 8 }, 'value': ')' }
             })
         })

diff --git a/src/parser/parser.ts b/src/parser/parser.ts
@@ -103,7 +103,7 @@ export class Parser {
         this.events.push({ type: 'advance' })
         this.pos++
         // TODO: attach comments to the preceding tree instead
-        if (skipIndependent && !this.eof() && independentTokenKinds.has(this.tokens[this.pos].kind)) {
+        if (skipIndependent && !this.eof() && independentTokenKinds.some(t => t === this.tokens[this.pos].kind)) {
             this.advance()
         }
     }
@@ -319,7 +319,7 @@ const parseConstrList = (parser: Parser): void => {
     while (!parser.at('c-brace') && !parser.eof()) {
         parseConstructor(parser)
         if (!parser.at('c-brace')) {
-            parser.consume('comma')
+            parser.expect('comma')
         }
     }
     parser.expect('c-brace')
@@ -540,7 +540,7 @@ const parseArgs = (parser: Parser): void => {
     while (!parser.at('c-paren') && !parser.eof()) {
         parseExpr(parser)
         if (!parser.at('c-paren')) {
-            parser.consume('comma')
+            parser.expect('comma')
         }
     }
     parser.expect('c-paren')
@@ -575,7 +575,7 @@ const parseLambdaParams = (parser: Parser): void => {
     while (!parser.at('pipe') && !parser.eof()) {
         parseParam(parser)
         if (!parser.at('pipe')) {
-            parser.consume('comma')
+            parser.expect('comma')
         }
     }
     parser.expect('pipe')
@@ -611,13 +611,16 @@ const parseParam = (parser: Parser): void => {
 }
 
 /**
- * block ::= O-BRACE statement* C-BRACE
+ * block ::= O-BRACE (statement (SEMI statement)* SEMI?)? C-BRACE
  */
 const parseBlock = (parser: Parser): void => {
     const mark = parser.open()
     parser.expect('o-brace')
-    while (parser.atAny(statementFirstTokens) && !parser.eof()) {
+    while (!parser.at('c-brace') && !parser.eof()) {
         parseStatement(parser)
+        if (!parser.at('c-brace')) {
+            parser.expect('semi')
+        }
     }
     parser.expect('c-brace')
     parser.close(mark, 'block')
@@ -654,7 +657,7 @@ const parseTypeParams = (parser: Parser): void => {
     while (!parser.at('c-angle') && !parser.eof()) {
         parseTypeExpr(parser)
         if (!parser.at('c-angle')) {
-            parser.consume('comma')
+            parser.expect('comma')
         }
     }
     parser.expect('c-angle')