From fbaa65a2319745c8a236a5c9c66e3406f42447c3 Mon Sep 17 00:00:00 2001
From: Thomas Voss <mail@thomasvoss.com>
Date: Mon, 24 Jun 2024 04:18:59 +0200
Subject: Support ‘…’ and ‘...’ in initializers
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 src/codegen.c |  4 ++++
 src/lexer.c   | 13 ++++++++++++-
 src/lexer.h   |  4 ++++
 src/parser.c  | 25 +++++++++++++++++++++----
 src/parser.h  |  5 +++--
 5 files changed, 44 insertions(+), 7 deletions(-)

(limited to 'src')

diff --git a/src/codegen.c b/src/codegen.c
index 6fc7848..665f071 100644
--- a/src/codegen.c
+++ b/src/codegen.c
@@ -240,6 +240,10 @@ codegendecl(struct cgctx ctx, idx_t i)
 
 	assert(ctx.ast.kinds[i] == ASTDECL);
 
+	/* Don’t assign a default value to ‘x: int = …’ */
+	if (ctx.aux.buf[p.lhs].decl.isundef)
+		return fwdnode(ctx.ast, i);
+
 	if (!ctx.types[i].isfloat && ctx.aux.buf[p.lhs].decl.isstatic) {
 		strview_t sv = ctx.toks.strs[ctx.ast.lexemes[i]];
 		/* TODO: Namespace the name */
diff --git a/src/lexer.c b/src/lexer.c
index 30686d8..a613585 100644
--- a/src/lexer.c
+++ b/src/lexer.c
@@ -70,6 +70,10 @@ lexstring(const uchar *code, size_t codesz)
 			data.kinds[data.len++] = ch;
 			break;
 
+		case RUNE_C(0x2026): /* U+2026 HORIZONTAL ELLIPSIS */
+			data.kinds[data.len++] = LEXELIP;
+			break;
+
 		/* Single- or double-byte literals */
 		case '/':
 			if (code < end && code[0] == '*') {
@@ -80,7 +84,6 @@ lexstring(const uchar *code, size_t codesz)
 
 			data.kinds[data.len++] = ch;
 			break;
-
 		case '<': case '>':
 			data.kinds[data.len++] = ch;
 
@@ -91,6 +94,13 @@ lexstring(const uchar *code, size_t codesz)
 			}
 			break;
 
+		case '.':
+			if (unlikely(end - code < 2) || code[0] != '.' || code[1] != '.')
+				goto fallback;
+			code += 2;
+			data.kinds[data.len++] = LEXELIP;
+			break;
+
 		case '0': case '1': case '2': case '3': case '4':
 		case '5': case '6': case '7': case '8': case '9':
 			data.kinds[data.len] = LEXNUM;
@@ -112,6 +122,7 @@ lexstring(const uchar *code, size_t codesz)
 			break;
 
 		default:
+fallback:
 			if (!rune_is_xids(ch))
 				continue;
 
diff --git a/src/lexer.h b/src/lexer.h
index 5436030..fb63fd8 100644
--- a/src/lexer.h
+++ b/src/lexer.h
@@ -13,6 +13,10 @@ enum {
 	LEXEOF,   /* End of token stream */
 	LEXIDENT, /* Identifier */
 	LEXNUM,   /* Numeric constant */
+	LEXELIP,  /* Ellipsis */
+
+	/* NOTE: Make sure that the enumerations above this comment don’t
+	   conflict with the following explicitly assigned enumerations! */
 
 	LEXAMP    = '&',
 	LEXCOLON  = ':',
diff --git a/src/parser.c b/src/parser.c
index 5b12e21..46a1fb6 100644
--- a/src/parser.c
+++ b/src/parser.c
@@ -128,6 +128,7 @@ parsedecl(ast_t *ast, aux_t *aux, lexemes_t toks, bool toplvl)
 	}
 
 	aux->buf[j].decl.isstatic = toplvl;
+	aux->buf[j].decl.isundef  = false;
 	if (toplvl && toks.kinds[toksidx] == LEXIDENT
 	    && strview_eq(SV("pub"), toks.strs[toksidx]))
 	{
@@ -165,11 +166,27 @@ parsedecl(ast_t *ast, aux_t *aux, lexemes_t toks, bool toplvl)
 		err("parser: Expected colon, equals, or semicolon");
 	}
 
-	bool func = toks.kinds[toksidx] == LEXLPAR;
-	if (func && ast->kinds[i] == ASTDECL)
-		err("Cannot assign function to mutable variable");
+	idx_t rhs;
+	bool func = false;
+
+	switch (toks.kinds[toksidx]) {
+	case LEXLPAR:
+		func = true;
+		if (ast->kinds[i] == ASTDECL)
+			err("Cannot assign function to mutable variable");
+		rhs = parsefunc(ast, aux, toks);
+		break;
+	case LEXELIP:
+		toksidx++;
+		if (ast->kinds[i] == ASTCDECL)
+			err("parser: Cannot assign to ‘…’ in constant declaration");
+		rhs = AST_EMPTY;
+		aux->buf[j].decl.isundef = true;
+		break;
+	default:
+		rhs = parseexpr(ast, aux, toks);
+	}
 
-	idx_t rhs = (func ? parsefunc : parseexpr)(ast, aux, toks);
 	ast->kids[i].rhs = rhs;
 	if (!func && toks.kinds[toksidx++] != LEXSEMI)
 		err("parser: Expected semicolon");
diff --git a/src/parser.h b/src/parser.h
index 9f7bf5e..d8991c0 100644
--- a/src/parser.h
+++ b/src/parser.h
@@ -71,8 +71,9 @@ typedef struct {
 	union {
 		struct {
 			idx_t type;
-			bool ispub;
-			bool isstatic;
+			bool ispub    : 1;
+			bool isstatic : 1;
+			bool isundef  : 1;
 		} decl;
 	} *buf;
 	size_t len, cap;
-- 
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