From 0c6bf5a7a97d2a1b9403506dd12226bfc68af461 Mon Sep 17 00:00:00 2001
From: Jean Pierre Cimalando <jp-dev@inbox.ru>
Date: Thu, 14 May 2020 21:24:24 +0200
Subject: [PATCH] parser: support recursive $-expansions

---
 src/sfizz/parser/Parser.cpp | 67 +++++++++++++++++++++++--------------
 tests/ParsingT.cpp          | 32 ++++++++++++++++++
 2 files changed, 73 insertions(+), 26 deletions(-)

diff --git a/src/sfizz/parser/Parser.cpp b/src/sfizz/parser/Parser.cpp
index 2c349e20..51eab71e 100644
--- a/src/sfizz/parser/Parser.cpp
+++ b/src/sfizz/parser/Parser.cpp
@@ -455,38 +455,53 @@ size_t Parser::extractToEol(Reader& reader, std::string* dst)
 std::string Parser::expandDollarVars(const SourceRange& range, absl::string_view src)
 {
     std::string dst;
+    std::string srcbuf; // temporary for retries when recursive
+    std::string name; // temporary for variable name
+    bool keepExpanding = true;
+
     dst.reserve(2 * src.size());
+    name.reserve(64);
 
-    size_t i = 0;
-    size_t n = src.size();
-    while (i < n) {
-        char c = src[i++];
+    while (keepExpanding) {
+        size_t i = 0;
+        size_t n = src.size();
+        size_t numExpansions = 0;
+        while (i < n) {
+            char c = src[i++];
 
-        if (c != '$')
-            dst.push_back(c);
-        else {
-            std::string name;
-            name.reserve(64);
+            if (c != '$')
+                dst.push_back(c);
+            else {
+                ++numExpansions;
+                name.clear();
 
-            // ARIA: we will accumulate any chars after $, until this is the
-            //       name of a known variable
-            auto def = _currentDefinitions.end();
-            while (i < n && isIdentifierChar(src[i]) && def == _currentDefinitions.end()) {
-                name.push_back(src[i++]);
-                def = _currentDefinitions.find(name);
+                // ARIA: we will accumulate any chars after $, until this is the
+                //       name of a known variable
+                auto def = _currentDefinitions.end();
+                while (i < n && isIdentifierChar(src[i]) && def == _currentDefinitions.end()) {
+                    name.push_back(src[i++]);
+                    def = _currentDefinitions.find(name);
+                }
+
+                if (name.empty()) {
+                    emitWarning(range, "Expected variable name after $.");
+                    continue;
+                }
+
+                if (def == _currentDefinitions.end()) {
+                    emitWarning(range, "The variable `" + name + "` is not defined.");
+                    continue;
+                }
+
+                dst.append(def->second);
             }
+        }
 
-            if (name.empty()) {
-                emitWarning(range, "Expected variable name after $.");
-                continue;
-            }
-
-            if (def == _currentDefinitions.end()) {
-                emitWarning(range, "The variable `" + name + "` is not defined.");
-                continue;
-            }
-
-            dst.append(def->second);
+        keepExpanding = numExpansions > 0;
+        if (keepExpanding) {
+            srcbuf = dst;
+            src = srcbuf;
+            dst.clear();
         }
     }
 
diff --git a/tests/ParsingT.cpp b/tests/ParsingT.cpp
index b259e4a7..2c4127d5 100644
--- a/tests/ParsingT.cpp
+++ b/tests/ParsingT.cpp
@@ -589,3 +589,35 @@ R"(#define $a foo #define $b bar <region> sample=$a-$b.wav
         REQUIRE(mock.fullBlockHeaders == expectedHeaders);
         REQUIRE(mock.fullBlockMembers == expectedMembers);
 }
+
+TEST_CASE("[Parsing] Recursive expansion")
+{
+        sfz::Parser parser;
+        ParsingMocker mock;
+        parser.setListener(&mock);
+        parser.parseString("/recursiveExpansion.sfz",
+R"(#define $B foo-$A-baz
+#define $A bar
+<region> sample=$B.wav)");
+
+        std::vector<std::vector<sfz::Opcode>> expectedMembers = {
+            {{"sample", "foo-bar-baz.wav"}},
+        };
+        std::vector<std::string> expectedHeaders = {
+            "region"
+        };
+        std::vector<sfz::Opcode> expectedOpcodes;
+
+        for (auto& members: expectedMembers)
+            for (auto& opcode: members)
+                expectedOpcodes.push_back(opcode);
+
+        REQUIRE(mock.beginnings == 1);
+        REQUIRE(mock.endings == 1);
+        REQUIRE(mock.errors.empty());
+        REQUIRE(mock.warnings.empty());
+        REQUIRE(mock.opcodes == expectedOpcodes);
+        REQUIRE(mock.headers == expectedHeaders);
+        REQUIRE(mock.fullBlockHeaders == expectedHeaders);
+        REQUIRE(mock.fullBlockMembers == expectedMembers);
+}