d: add an example

* examples/d/calc.test, examples/d/calc.y, examples/d/local.mk:
2026-03-19 01:03:04 +00:00 · 2018-11-30 08:17:57 +01:00
parent 0ebcae4a54
commit f15382f7d7
6 changed files with 227 additions and 3 deletions
--- a/examples/d/calc.y
+++ b/examples/d/calc.y
@@ -0,0 +1,161 @@
+%language "D"
+%name-prefix "Calc"
+%define parser_class_name {Calc}
+%define public
+
+%define parse.error verbose
+
+%code imports {
+  import std.ascii;
+  import std.stdio;
+}
+
+%union {
+  int ival;
+}
+
+/* Bison Declarations */
+%token EQ     "="
+       PLUS   "+"
+       MINUS  "-"
+       STAR   "*"
+       SLASH  "/"
+       BANG   "!"
+       LPAR   "("
+       RPAR   ")"
+       EOL    "end of line"
+%token <ival> NUM "number"
+%type  <ival> exp
+
+%nonassoc "="       /* comparison            */
+%left "-" "+"
+%left "*" "/"
+%precedence NEG     /* negation--unary minus */
+
+/* Grammar follows */
+%%
+input:
+  line
+| input line
+;
+
+line:
+  EOL
+| exp EOL           { writeln ($exp); }
+| error EOL
+;
+
+exp:
+  NUM                { $$ = $1; }
+| exp "=" exp
+  {
+    if ($1 != $3)
+      yyerror (format ("calc: error: %d != %d", $1, $3));
+  }
+| exp "+" exp        { $$ = $1 + $3; }
+| exp "-" exp        { $$ = $1 - $3; }
+| exp "*" exp        { $$ = $1 * $3; }
+| exp "/" exp        { $$ = $1 / $3; }
+| "-" exp  %prec NEG { $$ = -$2; }
+| "(" exp ")"        { $$ = $2; }
+| "(" error ")"      { $$ = 1111; }
+| "!"                { $$ = 0; return YYERROR; }
+| "-" error          { $$ = 0; return YYERROR; }
+;
+
+
+%%
+class CalcLexer : Lexer {
+
+  this ()
+    {}
+
+  int
+  get_char ()
+  {
+    import stdc = core.stdc.stdio;
+    return stdc.getc (stdc.stdin);
+  }
+
+  void
+  unget_char (int c)
+  {
+    import stdc = core.stdc.stdio;
+    stdc.ungetc (c, stdc.stdin);
+  }
+
+  public void yyerror (string s)
+  {
+    stderr.writeln (s);
+  }
+
+  int
+  read_signed_integer ()
+  {
+    int c = get_char ();
+    int sign = 1;
+    int n = 0;
+
+    if (c == '-')
+      {
+        c = get_char ();
+        sign = -1;
+      }
+
+    while (isDigit (c))
+      {
+        n = 10 * n + (c - '0');
+        c = get_char ();
+      }
+
+    unget_char (c);
+    return sign * n;
+  }
+
+  YYSemanticType semanticVal_;
+
+  public final @property YYSemanticType semanticVal()
+  {
+    return semanticVal_;
+  }
+
+  YYTokenType yylex ()
+  {
+    int c;
+    /* Skip white spaces.  */
+    do
+      {}
+    while ((c = get_char ()) == ' ' || c == '\t');
+
+    /* process numbers   */
+    if (c == '.' || isDigit (c))
+      {
+        unget_char (c);
+        semanticVal_.ival = read_signed_integer ();
+        return YYTokenType.NUM;
+      }
+
+    switch (c)
+      {
+      case EOF: return YYTokenType.EOF;
+      case '=': return YYTokenType.EQ;
+      case '+': return YYTokenType.PLUS;
+      case '-': return YYTokenType.MINUS;
+      case '*': return YYTokenType.STAR;
+      case '/': return YYTokenType.SLASH;
+      case '!': return YYTokenType.BANG;
+      case '(': return YYTokenType.LPAR;
+      case ')': return YYTokenType.RPAR;
+      case '\n': return YYTokenType.EOL;
+      default:  assert(0);
+      }
+  }
+}
+
+void main ()
+{
+  CalcLexer l = new CalcLexer ();
+  Calc p = new Calc (l);
+  p.parse ();
+}
+