big picture

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Aleksey Kladov 2018-12-18 00:13:50 +03:00
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commit ee2dc9969f

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@ -4,6 +4,33 @@ This document describes high-level architecture of rust-analyzer.
If you want to familiarize yourself with the code base, you are just
in the right place!
## The Big Picture
![](https://user-images.githubusercontent.com/1711539/50114578-e8a34280-0255-11e9-902c-7cfc70747966.png)
On the highest level, rust-analyzer is a thing which accepts input source code
from the client and produces a structured semantic model of the code.
More specifically, input data consists of a set of test files (`(PathBuf,
String)` pairs) and an information about project structure, the so called
`CrateGraph`. Crate graph specifies which files are crate roots, which cfg flags
are specified for each crate (TODO: actually implement this) and what are
dependencies between the crate. The analyzer keeps all these input data in
memory and never does any IO. Because the input data is source code, which
typically measures in tens of megabytes at most, keeping all input data in
memory is OK.
A "structured semantic model" is basically an object-oriented representations of
modules, functions and types which appear in the source code. This representation
is fully "resolved": all expressions have types, all references are bound to
declarations, etc.
The client can submit a small delta of input data (typically, a change to a
single file) and get a fresh code model which accounts for changes.
Underlying engine makes sure that model is computed lazily (on-demand) and can
be quickly updated for small modifications.
## Code generation
@ -86,7 +113,7 @@ current state, incorporates changes and handles out `Analysis` --- an
immutable consistent snapshot of world state at a point in time, which
actually powers analysis.
One interesting aspect of analysis is its support for cancelation. When a change
One interesting aspect of analysis is its support for cancellation. When a change
is applied to `AnalysisHost`, first all currently active snapshots are
cancelled. Only after all snapshots are dropped the change actually affects the
database.