ww: hare-feature batch (_, const, [_]T, ..., size/offset, assert, for-else)

lib/ww/lex/lex.ww

@@ -444,10 +444,18 @@ fn lexident(l: *lex, start: *pos, out: *tok) void = {
 	};
 	let n: u64 = l.lpos - begin;
 	let p: *u8 = l.src + begin;
-	let k: i32 = kwlookup(p, n: i32);
 	out.file = start.file;
 	out.line = start.line;
 	out.col  = start.col;
+	// Bare '_' is the discard marker. `_x`, `_1` are normal idents.
+	if (n == 1u64) {
+		if (p[0] == 95u8) {
+			out.kind = TK_UNDER;
+			out.text = astrndup(l.a, p, n);
+			return;
+		};
+	};
+	let k: i32 = kwlookup(p, n: i32);
 	if (k != TK_NONE) {
 		out.kind = k;
 	} else {

lib/ww/lex/tok.ww

@@ -48,62 +48,64 @@ def TK_FALSE:    i32 = 28;
 def TK_AS:       i32 = 29;
 def TK_STATIC:   i32 = 30;
 def TK_MATCH:    i32 = 31;
+def TK_CONST:    i32 = 32;
+def TK_UNDER:    i32 = 33;
 
-def TK_LPAREN:   i32 = 32;
-def TK_RPAREN:   i32 = 33;
-def TK_LBRACE:   i32 = 34;
-def TK_RBRACE:   i32 = 35;
-def TK_LBRACK:   i32 = 36;
-def TK_RBRACK:   i32 = 37;
-def TK_COMMA:    i32 = 38;
-def TK_SEMI:     i32 = 39;
-def TK_COLON:    i32 = 40;
-def TK_DOT:      i32 = 41;
-def TK_ELLIPSIS: i32 = 42;
-def TK_DOTDOT:   i32 = 43;
-def TK_AT:       i32 = 44;
-def TK_QUESTION: i32 = 45;
+def TK_LPAREN:   i32 = 34;
+def TK_RPAREN:   i32 = 35;
+def TK_LBRACE:   i32 = 36;
+def TK_RBRACE:   i32 = 37;
+def TK_LBRACK:   i32 = 38;
+def TK_RBRACK:   i32 = 39;
+def TK_COMMA:    i32 = 40;
+def TK_SEMI:     i32 = 41;
+def TK_COLON:    i32 = 42;
+def TK_DOT:      i32 = 43;
+def TK_ELLIPSIS: i32 = 44;
+def TK_DOTDOT:   i32 = 45;
+def TK_AT:       i32 = 46;
+def TK_QUESTION: i32 = 47;
 
-def TK_ASSIGN:    i32 = 46;
-def TK_PLUSEQ:    i32 = 47;
-def TK_MINUSEQ:   i32 = 48;
-def TK_STAREQ:    i32 = 49;
-def TK_SLASHEQ:   i32 = 50;
-def TK_PERCENTEQ: i32 = 51;
-def TK_AMPEQ:     i32 = 52;
-def TK_PIPEEQ:    i32 = 53;
-def TK_CARETEQ:   i32 = 54;
-def TK_LSHIFTEQ:  i32 = 55;
-def TK_RSHIFTEQ:  i32 = 56;
+def TK_ASSIGN:    i32 = 48;
+def TK_PLUSEQ:    i32 = 49;
+def TK_MINUSEQ:   i32 = 50;
+def TK_STAREQ:    i32 = 51;
+def TK_SLASHEQ:   i32 = 52;
+def TK_PERCENTEQ: i32 = 53;
+def TK_AMPEQ:     i32 = 54;
+def TK_PIPEEQ:    i32 = 55;
+def TK_CARETEQ:   i32 = 56;
+def TK_LSHIFTEQ:  i32 = 57;
+def TK_RSHIFTEQ:  i32 = 58;
 
-def TK_PLUS:    i32 = 57;
-def TK_MINUS:   i32 = 58;
-def TK_STAR:    i32 = 59;
-def TK_SLASH:   i32 = 60;
-def TK_PERCENT: i32 = 61;
-def TK_AMP:     i32 = 62;
-def TK_PIPE:    i32 = 63;
-def TK_CARET:   i32 = 64;
-def TK_TILDE:   i32 = 65;
-def TK_LSHIFT:  i32 = 66;
-def TK_RSHIFT:  i32 = 67;
+def TK_PLUS:    i32 = 59;
+def TK_MINUS:   i32 = 60;
+def TK_STAR:    i32 = 61;
+def TK_SLASH:   i32 = 62;
+def TK_PERCENT: i32 = 63;
+def TK_AMP:     i32 = 64;
+def TK_PIPE:    i32 = 65;
+def TK_CARET:   i32 = 66;
+def TK_TILDE:   i32 = 67;
+def TK_LSHIFT:  i32 = 68;
+def TK_RSHIFT:  i32 = 69;
 
-def TK_EQ:  i32 = 68;
-def TK_NEQ: i32 = 69;
-def TK_LT:  i32 = 70;
-def TK_LE:  i32 = 71;
-def TK_GT:  i32 = 72;
-def TK_GE:  i32 = 73;
+def TK_EQ:  i32 = 70;
+def TK_NEQ: i32 = 71;
+def TK_LT:  i32 = 72;
+def TK_LE:  i32 = 73;
+def TK_GT:  i32 = 74;
+def TK_GE:  i32 = 75;
 
-def TK_AND: i32 = 74;
-def TK_OR:  i32 = 75;
-def TK_NOT: i32 = 76;
+def TK_AND: i32 = 76;
+def TK_OR:  i32 = 77;
+def TK_NOT: i32 = 78;
 
-def TK_LARROW:   i32 = 77;
-def TK_ARROW:    i32 = 78;
-def TK_FATARROW: i32 = 79;
+def TK_LARROW:   i32 = 79;
+def TK_ARROW:    i32 = 80;
+def TK_FATARROW: i32 = 81;
 
-def TK_LAST: i32 = 80;
+def TK_LAST: i32 = 82;
 
 // ---- Pos / Tok --------------------------------------------------------
 //
@@ -152,6 +154,7 @@ export fn kwlookup(p: *u8, n: i32) i32 = {
 	if (streqn(p, "break", n))    { return TK_BREAK; };
 	if (streqn(p, "case", n))     { return TK_CASE; };
 	if (streqn(p, "chan", n))     { return TK_CHAN; };
+	if (streqn(p, "const", n))    { return TK_CONST; };
 	if (streqn(p, "continue", n)) { return TK_CONTINUE; };
 	if (streqn(p, "def", n))      { return TK_DEF; };
 	if (streqn(p, "defer", n))    { return TK_DEFER; };
@@ -214,6 +217,8 @@ export fn tokname(k: i32) str = {
 	if (k == TK_AS)       { return "as"; };
 	if (k == TK_STATIC)   { return "static"; };
 	if (k == TK_MATCH)    { return "match"; };
+	if (k == TK_CONST)    { return "const"; };
+	if (k == TK_UNDER)    { return "_"; };
 
 	if (k == TK_LPAREN)   { return "("; };
 	if (k == TK_RPAREN)   { return ")"; };