move the C sources to the subfolder pgf again for backwards compatibility

src/runtime/c/pgf/expr.h

@@ -0,0 +1,109 @@
+#ifndef EXPR_H_
+#define EXPR_H_
+
+/// An abstract syntax tree
+typedef variant PgfExpr;
+
+struct PgfHypo;
+struct PgfType;
+
+typedef int PgfMetaId;
+
+typedef enum {
+	PGF_BIND_TYPE_EXPLICIT,
+	PGF_BIND_TYPE_IMPLICIT
+} PgfBindType;
+
+/// A literal for an abstract syntax tree
+typedef variant PgfLiteral;
+
+struct PgfLiteralStr {
+    static const uint8_t tag = 0;
+
+	PgfText val;
+} ;
+
+struct PgfLiteralInt {
+    static const uint8_t tag = 1;
+
+	int val;
+} ;
+
+struct PgfLiteralFlt {
+    static const uint8_t tag = 2;
+
+	double val;
+};
+
+struct PgfHypo {
+	PgfBindType bind_type;
+	ref<PgfText> cid;
+	ref<PgfType> type;
+};
+
+struct PgfType {
+	ref<PgfVector<PgfHypo>> hypos;
+    ref<PgfVector<PgfExpr>> exprs;
+	PgfText name;
+};
+
+struct PgfExprAbs {
+    static const uint8_t tag = 0;
+    
+	PgfBindType bind_type;
+	PgfExpr body;
+	PgfText name;
+};
+
+struct PgfExprApp {
+    static const uint8_t tag = 1;
+
+	PgfExpr fun;
+	PgfExpr arg;
+};
+
+struct PgfExprLit {
+    static const uint8_t tag = 2;
+
+	PgfLiteral lit;
+};
+
+struct PgfExprMeta {
+    static const uint8_t tag = 3;
+
+	PgfMetaId id;
+};
+
+struct PgfExprFun {
+    static const uint8_t tag = 4;
+
+	PgfText name;
+};
+
+struct PgfExprVar {
+    static const uint8_t tag = 5;
+    
+	int var;
+};
+
+struct PgfExprTyped {
+    static const uint8_t tag = 6;
+
+	PgfExpr expr;
+	ref<PgfType> type;
+};
+
+struct PgfExprImplArg {
+    static const uint8_t tag = 7;
+
+	PgfExpr expr;
+};
+
+typedef float prob_t;
+
+typedef struct {
+	prob_t prob;
+	PgfExpr expr;
+} PgfExprProb;
+
+#endif /* EXPR_H_ */