Support the ternary operator.

8 files changed, 89 insertions, 50 deletions

diff --git a/dimension/common.nonterminals b/dimension/common.nonterminals
index 2008290..164440a 100644
--- a/dimension/common.nonterminals
+++ b/dimension/common.nonterminals
@@ -73,6 +73,7 @@
 
 /* Generalized arithmetic expressions */
 %type <astnode> ARITH_EXPR
+%type <astnode> CONDITIONAL
 %type <astnode> MAX_LIST
 %type <astnode> MIN_LIST
 
diff --git a/dimension/common.rules b/dimension/common.rules
index 02f2010..81719c5 100644
--- a/dimension/common.rules
+++ b/dimension/common.rules
@@ -395,7 +395,10 @@ ARITH_EXPR: FLOAT_LITERAL
           | ARITH_EXPR "." "transmit" {
             $$ = dmnsn_new_astnode1(DMNSN_AST_DOT_TRANSMIT, @$, $1);
           }
-          | "(" ARITH_EXPR ")" { $$ = $2; }
+          | "(" ARITH_EXPR ")" %dprec 2 { $$ = $2; }
+          | "(" CONDITIONAL "?" ARITH_EXPR ":" ARITH_EXPR ")" {
+            $$ = dmnsn_new_astnode3(DMNSN_AST_TERNARY, @$, $2, $4, $6);
+          }
           | "abs" "(" ARITH_EXPR ")" {
             $$ = dmnsn_new_astnode1(DMNSN_AST_ABS, @$, $3);
           }
@@ -530,6 +533,43 @@ MIN_LIST: ARITH_EXPR "," ARITH_EXPR {
         }
 ;
 
+CONDITIONAL: ARITH_EXPR {
+             /* Force the expression to be evaluated logically */
+             dmnsn_astnode zero = dmnsn_new_ast_integer(0);
+             $$ = dmnsn_new_astnode2(DMNSN_AST_OR, @$, zero, $1);
+           }
+           | ARITH_EXPR "="  ARITH_EXPR {
+             $$ = dmnsn_new_astnode2(DMNSN_AST_EQUAL, @$, $1, $3);
+           }
+           | ARITH_EXPR "!=" ARITH_EXPR {
+             $$ = dmnsn_new_astnode2(DMNSN_AST_NOT_EQUAL, @$, $1, $3);
+           }
+           | ARITH_EXPR "<"  ARITH_EXPR {
+             $$ = dmnsn_new_astnode2(DMNSN_AST_LESS, @$, $1, $3);
+           }
+           | ARITH_EXPR "<=" ARITH_EXPR {
+             $$ = dmnsn_new_astnode2(DMNSN_AST_LESS_EQUAL, @$, $1, $3);
+           }
+           | ARITH_EXPR ">"  ARITH_EXPR {
+             $$ = dmnsn_new_astnode2(DMNSN_AST_GREATER, @$, $1, $3);
+           }
+           | ARITH_EXPR ">=" ARITH_EXPR {
+             $$ = dmnsn_new_astnode2(DMNSN_AST_GREATER_EQUAL, @$, $1, $3);
+           }
+           | CONDITIONAL "&" CONDITIONAL {
+             $$ = dmnsn_new_astnode2(DMNSN_AST_AND, @$, $1, $3);
+           }
+           | CONDITIONAL "|" CONDITIONAL {
+             $$ = dmnsn_new_astnode2(DMNSN_AST_OR, @$, $1, $3);
+           }
+           | "(" CONDITIONAL ")" %dprec 1 {
+             $$ = $2;
+           }
+           | "!" CONDITIONAL {
+             $$ = dmnsn_new_astnode1(DMNSN_AST_NOT, @$, $2);
+           }
+;
+
 /* Colors */
 
 COLOR: COLOR_BODY {
diff --git a/dimension/directives.nonterminals b/dimension/directives.nonterminals
index 5738bcd..6f858af 100644
--- a/dimension/directives.nonterminals
+++ b/dimension/directives.nonterminals
@@ -20,5 +20,3 @@
  *************************************************************************/
 
 %type <astnode> RVALUE
-
-%type <astnode> CONDITIONAL
diff --git a/dimension/directives.rules b/dimension/directives.rules
index a01ab9a..b995c78 100644
--- a/dimension/directives.rules
+++ b/dimension/directives.rules
@@ -70,6 +70,7 @@ LANGUAGE_DIRECTIVE: "#include" STRING {
                     dmnsn_delete_astnode($2);
                     YYERROR;
                   }
+;
 
 RVALUE: ARITH_EXPR ";" %dprec 2 {
         $$ = dmnsn_eval($1, symtable);
@@ -88,39 +89,4 @@ RVALUE: ARITH_EXPR ";" %dprec 2 {
       | INTERIOR
       | CAMERA
       | TRANSFORMATION
-
-CONDITIONAL: ARITH_EXPR {
-             /* Force the expression to be evaluated logically */
-             dmnsn_astnode zero = dmnsn_new_ast_integer(0);
-             $$ = dmnsn_new_astnode2(DMNSN_AST_OR, @$, zero, $1);
-           }
-           | ARITH_EXPR "="  ARITH_EXPR {
-             $$ = dmnsn_new_astnode2(DMNSN_AST_EQUAL, @$, $1, $3);
-           }
-           | ARITH_EXPR "!=" ARITH_EXPR {
-             $$ = dmnsn_new_astnode2(DMNSN_AST_NOT_EQUAL, @$, $1, $3);
-           }
-           | ARITH_EXPR "<"  ARITH_EXPR {
-             $$ = dmnsn_new_astnode2(DMNSN_AST_LESS, @$, $1, $3);
-           }
-           | ARITH_EXPR "<=" ARITH_EXPR {
-             $$ = dmnsn_new_astnode2(DMNSN_AST_LESS_EQUAL, @$, $1, $3);
-           }
-           | ARITH_EXPR ">"  ARITH_EXPR {
-             $$ = dmnsn_new_astnode2(DMNSN_AST_GREATER, @$, $1, $3);
-           }
-           | ARITH_EXPR ">=" ARITH_EXPR {
-             $$ = dmnsn_new_astnode2(DMNSN_AST_GREATER_EQUAL, @$, $1, $3);
-           }
-           | CONDITIONAL "&" CONDITIONAL {
-             $$ = dmnsn_new_astnode2(DMNSN_AST_AND, @$, $1, $3);
-           }
-           | CONDITIONAL "|" CONDITIONAL {
-             $$ = dmnsn_new_astnode2(DMNSN_AST_OR, @$, $1, $3);
-           }
-           | "(" CONDITIONAL ")" {
-             $$ = $2;
-           }
-           | "!" CONDITIONAL {
-             $$ = dmnsn_new_astnode1(DMNSN_AST_NOT, @$, $2);
-           }
+;
diff --git a/dimension/grammar.declarations b/dimension/grammar.declarations
index 363554e..3eae498 100644
--- a/dimension/grammar.declarations
+++ b/dimension/grammar.declarations
@@ -23,7 +23,7 @@
 
 %name-prefix "dmnsn_yy"
 
-%expect 7
+%expect 8
 
 %parse-param {const char *filename}
 %parse-param {void *yyscanner}
diff --git a/dimension/grammar.epilogue b/dimension/grammar.epilogue
index 881ec98..6b93dc3 100644
--- a/dimension/grammar.epilogue
+++ b/dimension/grammar.epilogue
@@ -178,6 +178,7 @@ dmnsn_astnode_string(dmnsn_astnode_type astnode_type)
   dmnsn_astnode_map(DMNSN_AST_AND,           "&" );
   dmnsn_astnode_map(DMNSN_AST_OR,            "|" );
   dmnsn_astnode_map(DMNSN_AST_NOT,           "!" );
+  dmnsn_astnode_map(DMNSN_AST_TERNARY,       "?:");
 
   dmnsn_astnode_map(DMNSN_AST_ABS,     "abs"    );
   dmnsn_astnode_map(DMNSN_AST_ACOS,    "acos"   );
diff --git a/dimension/parse.c b/dimension/parse.c
index 0f94f6c..52479ad 100644
--- a/dimension/parse.c
+++ b/dimension/parse.c
@@ -1413,6 +1413,35 @@ dmnsn_eval_binary(dmnsn_astnode astnode, dmnsn_symbol_table *symtable)
   return ret;
 }
 
+static dmnsn_astnode
+dmnsn_eval_ternary(dmnsn_astnode astnode, dmnsn_symbol_table *symtable)
+{
+  dmnsn_astnode test, iftrue, iffalse, ret;
+  dmnsn_array_get(astnode.children, 0, &test);
+  dmnsn_array_get(astnode.children, 1, &iftrue);
+  dmnsn_array_get(astnode.children, 2, &iffalse);
+  test = dmnsn_eval_scalar(test, symtable);
+
+  switch(astnode.type) {
+  case DMNSN_AST_TERNARY:
+    dmnsn_assert(test.type == DMNSN_AST_INTEGER,
+                 "Conditional expression evaluated to non-integer.");
+    ret = dmnsn_eval(*(long *)test.ptr ? iftrue : iffalse, symtable);
+    break;
+
+  default:
+    dmnsn_diagnostic(astnode.filename, astnode.line, astnode.col,
+                     "invalid ternary operator '%s'",
+                     dmnsn_astnode_string(astnode.type));
+    ret = dmnsn_copy_astnode(astnode);
+    ret.type = DMNSN_AST_NONE;
+    break;
+  }
+
+  dmnsn_delete_astnode(test);
+  return ret;
+}
+
 dmnsn_astnode
 dmnsn_eval(dmnsn_astnode astnode, dmnsn_symbol_table *symtable)
 {
@@ -1513,6 +1542,9 @@ dmnsn_eval(dmnsn_astnode astnode, dmnsn_symbol_table *symtable)
   case DMNSN_AST_VDOT:
     return dmnsn_eval_binary(astnode, symtable);
 
+  case DMNSN_AST_TERNARY:
+    return dmnsn_eval_ternary(astnode, symtable);
+
   default:
     dmnsn_diagnostic(astnode.filename, astnode.line, astnode.col,
                      "expected arithmetic expression; found %s",
diff --git a/dimension/parse.h b/dimension/parse.h
index 09931d1..ef5bb17 100644
--- a/dimension/parse.h
+++ b/dimension/parse.h
@@ -90,6 +90,17 @@ typedef enum {
   DMNSN_AST_DOT_T,
   DMNSN_AST_DOT_TRANSMIT,
 
+  DMNSN_AST_EQUAL,
+  DMNSN_AST_NOT_EQUAL,
+  DMNSN_AST_LESS,
+  DMNSN_AST_LESS_EQUAL,
+  DMNSN_AST_GREATER,
+  DMNSN_AST_GREATER_EQUAL,
+  DMNSN_AST_AND,
+  DMNSN_AST_OR,
+  DMNSN_AST_NOT,
+  DMNSN_AST_TERNARY,
+
   DMNSN_AST_ABS,
   DMNSN_AST_ACOS,
   DMNSN_AST_ACOSH,
@@ -133,16 +144,6 @@ typedef enum {
   DMNSN_AST_Z,
   DMNSN_AST_T,
 
-  DMNSN_AST_EQUAL,
-  DMNSN_AST_NOT_EQUAL,
-  DMNSN_AST_LESS,
-  DMNSN_AST_LESS_EQUAL,
-  DMNSN_AST_GREATER,
-  DMNSN_AST_GREATER_EQUAL,
-  DMNSN_AST_AND,
-  DMNSN_AST_OR,
-  DMNSN_AST_NOT,
-
   DMNSN_AST_IDENTIFIER,
 
   DMNSN_AST_STRING,