itsscb/rust-analyzer
1
0
Fork 0
mirror of https://github.com/rust-lang/rust-analyzer.git synced 2025-10-01 11:31:15 +00:00
Code Issues Packages Projects Releases Wiki Activity

add illustrations

Browse Source
This commit is contained in:
Aleksey Kladov 2019-01-21 11:18:40 +03:00
parent 9b0aa786ee
commit 5a4276b1af
1 changed files with 12 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
guide.md
View File

@ -227,8 +227,8 @@ of type `V`. Queries come in two basic varieties:
For further discussion, its important to understand one bit of "fairly For further discussion, its important to understand one bit of "fairly
intelligently". Suppose we have two functions, `f1` and `f2`, and one input, `z`. intelligently". Suppose we have two functions, `f1` and `f2`, and one input,
We call `f1(X)` which in turn calls `f2(Y)` which inspects `i(Z)`. `i(Z)` `z`. We call `f1(X)` which in turn calls `f2(Y)` which inspects `i(Z)`. `i(Z)`
returns some value `V1`, `f2` uses that and returns `R1`, `f1` uses that and returns some value `V1`, `f2` uses that and returns `R1`, `f1` uses that and
returns `O`. Now, let's change `i` at `Z` to `V2` from `V1` and try to compute returns `O`. Now, let's change `i` at `Z` to `V2` from `V1` and try to compute
`f1(X)` again. Because `f1(X)` (transitively) depends on `i(Z)`, we can't just `f1(X)` again. Because `f1(X)` (transitively) depends on `i(Z)`, we can't just
@ -236,7 +236,16 @@ reuse its value as is. However, if `f2(Y)` is *still* equal to `R1` (despite
`i`'s change), we, in fact, *can* reuse `O` as result of `f1(X)`. And that's how `i`'s change), we, in fact, *can* reuse `O` as result of `f1(X)`. And that's how
salsa works: it recomputes results in *reverse* order, starting from inputs and salsa works: it recomputes results in *reverse* order, starting from inputs and
progressing towards outputs, stopping as soon as it sees an intermediate value progressing towards outputs, stopping as soon as it sees an intermediate value
that hasn't changed. that hasn't changed. If this sounds confusing to you, don't worry: it is
confusing. This illustration by @killercup might help:
<img alt="step 1" src="https://user-images.githubusercontent.com/1711539/51460907-c5484780-1d6d-11e9-9cd2-d6f62bd746e0.png" width="50%">
<img alt="step 2" src="https://user-images.githubusercontent.com/1711539/51460915-c9746500-1d6d-11e9-9a77-27d33a0c51b5.png" width="50%">
<img alt="step 3" src="https://user-images.githubusercontent.com/1711539/51460920-cda08280-1d6d-11e9-8d96-a782aa57a4d4.png" width="50%">
<img alt="step 4" src="https://user-images.githubusercontent.com/1711539/51460927-d1340980-1d6d-11e9-851e-13c149d5c406.png" width="50%">
## Salsa Input Queries ## Salsa Input Queries