workflows: add check for generated AT Parser

Adds check for generated AT Parser lexer to determine
if it's up to date according to the regex source.

Signed-off-by: Mirko Covizzi <[email protected]>

.github/workflows/check-generated-lexer.yml

@@ -0,0 +1,38 @@
+name: Check Generated AT Parser Lexer
+
+on:
+  pull_request:
+    paths:
+      - 'lib/at_parser/at_match.re'
+
+jobs:
+  compliance_job:
+    runs-on: ubuntu-latest
+    name: Check Generated AT Parser Lexer
+    steps:
+    - name: Update PATH for west
+      run: |
+        echo "$HOME/.local/bin" >> $GITHUB_PATH
+
+    - name: Checkout sources
+      uses: nrfconnect/action-checkout-west-update@main
+      with:
+        git-fetch-depth: 0
+        git-ref: ${{ github.event.pull_request.head.sha }}
+
+    - name: Install dependencies
+      run: |
+        sudo apt-get install re2c
+
+    - name: Generate lexer
+      run: |
+        re2c at_match.re -o at_match.c -W --no-debug-info --tags
+
+    - name: Compare lexers
+      run: |
+        if diff -q at_match.c ncs/nrf/lib/at_parser/generated/at_match.c > /dev/null; then
+          echo "Lexer is up to date."
+        else
+          echo "Lexer is not up to date. Please re-generate the lexer and update the PR."
+          exit 1
+        fi