Added Python-style if/else expression keywords

5 files changed, 66 insertions, 3 deletions

diff --git a/src/commodity.cc b/src/commodity.cc
index 08252cf4..243d2a6c 100644
--- a/src/commodity.cc
+++ b/src/commodity.cc
@@ -473,8 +473,12 @@ namespace {
       return std::strcmp(buf, "and") == 0;
     case 'd':
       return std::strcmp(buf, "div") == 0;
+    case 'e':
+      return std::strcmp(buf, "else") == 0;
     case 'f':
       return std::strcmp(buf, "false") == 0;
+    case 'i':
+      return std::strcmp(buf, "if") == 0;
     case 'o':
       return std::strcmp(buf, "or") == 0;
     case 'n':
diff --git a/src/generate.cc b/src/generate.cc
index 725c4a6c..6d1bfb1a 100644
--- a/src/generate.cc
+++ b/src/generate.cc
@@ -171,7 +171,8 @@ void generate_posts_iterator::generate_commodity(std::ostream& out)
   }
   while (comm == "h" || comm == "m" || comm == "s" ||
 	 comm == "and" || comm == "div" || comm == "false" ||
-	 comm == "or" || comm == "not" || comm == "true");
+	 comm == "or" || comm == "not" || comm == "true" ||
+	 comm == "if" || comm == "else");
 
   out << comm;
 }
diff --git a/src/parser.cc b/src/parser.cc
index 396d3a64..b3457f08 100644
--- a/src/parser.cc
+++ b/src/parser.cc
@@ -382,7 +382,41 @@ expr_t::parser_t::parse_querycolon_expr(std::istream& in,
 	       _("%1 operator not followed by argument") << tok.symbol);
 
       node->set_right(subnode);
-    } else {
+    }
+    else if (tok.kind == token_t::KW_IF) {
+      ptr_op_t if_op(parse_or_expr(in, tflags));
+      if (! if_op)
+	throw_(parse_error, _("'if' keyword not followed by argument"));
+
+      tok = next_token(in, tflags.plus_flags(PARSE_OP_CONTEXT));
+      if (tok.kind == token_t::KW_ELSE) {
+	ptr_op_t else_op(parse_or_expr(in, tflags));
+	if (! else_op)
+	  throw_(parse_error, _("'else' keyword not followed by argument"));
+
+	ptr_op_t subnode = new op_t(op_t::O_COLON);
+	subnode->set_left(node);
+	subnode->set_right(else_op);
+
+	node = new op_t(op_t::O_QUERY);
+	node->set_left(if_op);
+	node->set_right(subnode);
+      } else {
+	ptr_op_t null_node = new op_t(op_t::VALUE);
+	null_node->set_value(NULL_VALUE);
+
+	ptr_op_t subnode = new op_t(op_t::O_COLON);
+	subnode->set_left(node);
+	subnode->set_right(null_node);
+
+	node = new op_t(op_t::O_QUERY);
+	node->set_left(if_op);
+	node->set_right(subnode);
+
+	push_token(tok);
+      }
+    }
+    else {
       push_token(tok);
     }
   }
diff --git a/src/token.cc b/src/token.cc
index 6935bc7a..0a8fce7e 100644
--- a/src/token.cc
+++ b/src/token.cc
@@ -38,7 +38,8 @@ int expr_t::token_t::parse_reserved_word(std::istream& in)
 {
   char c = static_cast<char>(in.peek());
 
-  if (c == 'a' || c == 'd' || c == 'f' || c == 'o' || c == 'n' || c == 't') {
+  if (c == 'a' || c == 'd' || c == 'e' || c == 'f' ||
+      c == 'i' || c == 'o' || c == 'n' || c == 't') {
     length = 0;
 
     char buf[6];
@@ -64,6 +65,16 @@ int expr_t::token_t::parse_reserved_word(std::istream& in)
       }
       break;
 
+    case 'e':
+      if (std::strcmp(buf, "else") == 0) {
+	symbol[0] = 'L';
+	symbol[1] = 'S';
+	symbol[2] = '\0';
+	kind = KW_ELSE;
+	return 1;
+      }
+      break;
+
     case 'f':
       if (std::strcmp(buf, "false") == 0) {
 	kind = VALUE;
@@ -72,6 +83,16 @@ int expr_t::token_t::parse_reserved_word(std::istream& in)
       }
       break;
 
+    case 'i':
+      if (std::strcmp(buf, "if") == 0) {
+	symbol[0] = 'i';
+	symbol[1] = 'f';
+	symbol[2] = '\0';
+	kind = KW_IF;
+	return 1;
+      }
+      break;
+
     case 'o':
       if (std::strcmp(buf, "or") == 0) {
 	symbol[0] = '|';
diff --git a/src/token.h b/src/token.h
index d0b65ded..7b5eec11 100644
--- a/src/token.h
+++ b/src/token.h
@@ -88,6 +88,9 @@ struct expr_t::token_t : public noncopyable
     KW_OR,			// |, ||, or
     KW_MOD,			// %
 
+    KW_IF,			// if
+    KW_ELSE,			// else
+
     QUERY,			// ?
     COLON,			// :