Decouple log targets to a separate crate (#152)

crates/air-lib/trace-handler/src/data_keeper/merge_ctx.rs

@@ -0,0 +1,79 @@
+/*
+ * Copyright 2021 Fluence Labs Limited
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+use super::ExecutionTrace;
+use super::KeeperError;
+use super::KeeperResult;
+use super::TraceSlider;
+
+use air_interpreter_data::InterpreterData;
+use air_interpreter_data::StreamGenerations;
+
+use std::collections::HashMap;
+
+/// Contains all necessary information about data.
+#[derive(Debug, Default, PartialEq)]
+pub struct MergeCtx {
+    pub slider: TraceSlider,
+    pub streams: StreamGenerations,
+}
+
+impl MergeCtx {
+    #[allow(dead_code)]
+    pub(crate) fn from_trace(trace: ExecutionTrace) -> Self {
+        let slider = TraceSlider::new(trace);
+
+        Self {
+            slider,
+            streams: HashMap::new(),
+        }
+    }
+
+    pub(crate) fn from_data(data: InterpreterData) -> Self {
+        let slider = TraceSlider::new(data.trace);
+
+        Self {
+            slider,
+            streams: data.streams,
+        }
+    }
+
+    pub(crate) fn try_get_generation(&self, position: u32) -> KeeperResult<u32> {
+        use air_interpreter_data::*;
+
+        let position = position as usize;
+        let state = self
+            .slider
+            .state_at_position(position)
+            .ok_or_else(|| KeeperError::NoElementAtPosition {
+                position,
+                trace_len: self.slider.trace_len(),
+            })?;
+
+        match state {
+            ExecutedState::Call(CallResult::Executed(Value::Stream { generation, .. })) => Ok(*generation),
+            // such Aps are always preceded by Fold where corresponding stream could be used,
+            // so it's been already checked that res_generation is well-formed
+            // and accessing 0th element is safe here
+            ExecutedState::Ap(ap_result) => Ok(ap_result.res_generations[0]),
+            state => Err(KeeperError::NoStreamState { state: state.clone() }),
+        }
+    }
+
+    pub(crate) fn stream_generation(&self, stream_name: &str) -> Option<u32> {
+        self.streams.get(stream_name).copied()
+    }
+}