feat: Add APPROXIMATE function keyword support

.github/workflows/rust.yml

@@ -11,11 +11,9 @@ jobs:
         uses: hecrj/setup-rust-action@v1
         with:
           components: rustfmt
-          # Note that `nightly` is required for `license_template_path`, as
-          # it's an unstable feature.
-          rust-version: nightly
+          rust-version: nightly-2022-03-08
       - uses: actions/checkout@v2
-      - run: cargo +nightly fmt -- --check --config-path <(echo 'license_template_path = "HEADER"')
+      - run: cargo fmt -- --check --config-path <(echo 'license_template_path = "HEADER"')
 
   lint:
     runs-on: ubuntu-latest
@@ -24,6 +22,7 @@ jobs:
         uses: hecrj/setup-rust-action@v1
         with:
           components: clippy
+          rust-version: nightly-2022-03-08
       - uses: actions/checkout@v2
       - run: cargo clippy --all-targets --all-features -- -D warnings
 
@@ -42,13 +41,14 @@ jobs:
         uses: hecrj/setup-rust-action@v1
         with:
           targets: 'thumbv6m-none-eabi'
+          rust-version: nightly-2022-03-08
       - uses: actions/checkout@master
       - run: cargo check --no-default-features --target thumbv6m-none-eabi
 
   test:
     strategy:
       matrix:
-        rust: [stable, beta, nightly]
+        rust: [stable, beta, nightly, nightly-2022-03-08]
     runs-on: ubuntu-latest
     steps:
     - name: Setup Rust

.gitignore

@@ -3,10 +3,6 @@
 /target/
 /sqlparser_bench/target/
 
-# Remove Cargo.lock from gitignore if creating an executable, leave it for libraries
-# More information here http://doc.crates.io/guide.html#cargotoml-vs-cargolock
-Cargo.lock
-
 # These are backup files generated by rustfmt
 **/*.rs.bk
 

rust-toolchain

@@ -1 +1 @@
-stable
+nightly-2022-03-08

src/ast/mod.rs

@@ -2231,10 +2231,15 @@ pub struct Function {
     // aggregate functions may specify eg `COUNT(DISTINCT x)`
     pub distinct: bool,
     pub special: bool,
+    // Redshift provides `APPROXIMATE` option for some functions, e.g. `COUNT`
+    pub approximate: bool,
 }
 
 impl fmt::Display for Function {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        if self.approximate {
+            write!(f, "APPROXIMATE ")?;
+        }
         if self.special {
             write!(f, "{}", self.name)?;
         } else {

src/keywords.rs

@@ -77,6 +77,7 @@ define_keywords!(
     AND,
     ANY,
     APPLY,
+    APPROXIMATE,
     ARE,
     ARRAY,
     ARRAY_AGG,