started a new database-backed runtime from scratch

src/runtime/c/expr.h

@@ -0,0 +1,30 @@
+#ifndef EXPR_H_
+#define EXPR_H_
+
+#include "variant.h"
+
+// PgfLiteral
+
+typedef variant PgfLiteral;
+
+
+typedef enum {
+	PGF_LITERAL_STR,
+	PGF_LITERAL_INT,
+	PGF_LITERAL_FLT,
+	PGF_LITERAL_NUM_TAGS
+} PgfLiteralTag;
+
+typedef struct {
+	char val[0];  // a flexible array that contains the value
+} PgfLiteralStr;
+
+typedef struct {
+	int val;
+} PgfLiteralInt;
+
+typedef struct {
+	double val;
+} PgfLiteralFlt;
+
+#endif /* EXPR_H_ */