Implement stream producers that emit characters or lines

src/sensesp/system/stream_producer.h

@@ -0,0 +1,67 @@
+#ifndef SENSESP_SRC_SENSESP_SYSTEM_STREAM_PRODUCER_H_
+#define SENSESP_SRC_SENSESP_SYSTEM_STREAM_PRODUCER_H_
+
+#include "sensesp.h"
+
+#include "ReactESP.h"
+#include "sensesp/system/valueproducer.h"
+
+namespace sensesp {
+
+/**
+ * @brief ValueProducer that reads from a Stream and produces each character.
+ */
+class StreamCharProducer : public ValueProducer<char> {
+ public:
+  StreamCharProducer(Stream* stream) : stream_{stream} {
+    read_reaction_ = ReactESP::app->onAvailable(*stream_, [this]() {
+      while (stream_->available()) {
+        char c = stream_->read();
+        this->emit(c);
+      }
+    });
+  }
+
+ protected:
+  Stream* stream_;
+  StreamReaction* read_reaction_;
+};
+
+/**
+ * @brief ValueProducer that reads from a Stream and produces a full line.
+ */
+class StreamLineProducer : public ValueProducer<String> {
+ public:
+  StreamLineProducer(Stream* stream, int max_line_length = 256)
+      : stream_{stream}, max_line_length_{max_line_length} {
+    static int buf_pos = 0;
+    buf_ = new char[max_line_length_ + 1];
+    read_reaction_ = ReactESP::app->onAvailable(*stream_, [this]() {
+      while (stream_->available()) {
+        char c = stream_->read();
+        if (c == '\n') {
+          // Include the newline character in the output
+          buf_[buf_pos++] = c;
+          buf_[buf_pos] = '\0';
+          this->emit(buf_);
+          buf_pos = 0;
+        } else {
+          buf_[buf_pos++] = c;
+          if (buf_pos >= max_line_length_ - 1) {
+            buf_pos = 0;
+          }
+        }
+      }
+    });
+  }
+
+ protected:
+  const int max_line_length_;
+  char *buf_;
+  Stream* stream_;
+  StreamReaction* read_reaction_;
+};
+
+}  // namespace sensesp
+
+#endif  // SENSESP_SRC_SENSESP_SYSTEM_STREAM_PRODUCER_H_