* AST Sample for Javascript Source
  Create dot output from query and db, and then get a rendered graph in SVG.

  #+BEGIN_SRC sh
    # 
    export PATH=$HOME/local/vmsync/codeql250:"$PATH"

    # 
    cd ~/w/codeql-javascript/src/
    codeql database create -j8 -v --language=javascript -s . callbacks.db

    # 
    cd ~/w/codeql-javascript/queries/
    codeql database analyze                                 \
           ~/w/codeql-javascript/src/callbacks.db/          \
           ~/w/codeql-javascript/queries/printast.ql        \
           -j8 -v --ram=16000                               \
           --format=dot                                     \
           --output=printast.dot

    # Results in 
    ls ./callbacks.db/results/codeql-custom-queries-javascript/printast.bqrs
    # and
    ls ./printast.dot/null.dot

    # 
    cd ~/w/codeql-javascript/src/
    dot -Tsvg < ./printast.dot/null.dot > ./printast.dot/null.svg
    open -a safari printast.dot/null.svg

  #+END_SRC

  #+CAPTION: AST graph from dot
  #+NAME:   fig:graph-ast-1
  [[./src/printast.dot/null.svg]]

* Correspondence between query and graph
** Node Query
  : query predicate nodes(PrintAstNode node, string key, string value)

  query result
  | node                     | key          | value                    |
  |--------------------------+--------------+--------------------------|
  | [DeclStmt] var arr = ... | semmle.label | [DeclStmt] var arr = ... |

  dot source in [[./src/printast.dot/null.dot]]
  #+BEGIN_SRC text
    digraph {
      28[label="[DeclStmt] var arr = ..."; ];
    }
  #+END_SRC

 
** Edge Query
  : query predicate edges(PrintAstNode source, PrintAstNode target, string key, string value)

  query result
  | source                      | target                                  | key          | value |
  |-----------------------------+-----------------------------------------+--------------+-------|
  | [DeclStmt] var result = ... | [VariableDeclarator] result ... > 3; }) | semmle.order |     1 |
  | [DeclStmt] var result = ... | [VariableDeclarator] result ... > 3; }) | semmle.label |     1 |

  dot source in [[./src/printast.dot/null.dot]]
  #+BEGIN_SRC text
    digraph {
      29[label="[DeclStmt] var result = ..."; ];
      9[label="[VariableDeclarator] result ... > 3; })"; ];

      29 -> 9[label="1"; ];
    }
  #+END_SRC

 
** graph properties
   #+BEGIN_SRC java
     query predicate graphProperties(string key, string value) {
       key = "semmle.graphKind" and value = "tree"
     }
   #+END_SRC

   query result
   | key              | value |
   |------------------+-------|
   | semmle.graphKind | tree  |

   dot source: none

* Simple direct use of graph API
  For illustration, the query [[./queries/graphout.ql]] uses the =@kind graph= output
  for a trivial graph defined in the =edges()= predicate.

  The ouput: 
  #+CAPTION: Trivial graph rendered by dot
  #+ATTR_HTML: :width 10% :height 180px
  #+NAME:   fig:graph-trivial-1
  [[./printast.dot/null.svg]]

  #+BEGIN_SRC sh
    # 
    export PATH=$HOME/local/vmsync/codeql250:"$PATH"

    # Create the db
    cd ~/w/codeql-javascript/src/
    rm -fR callbacks.db
    codeql database create -j8 -v --language=javascript -s . callbacks.db

    # Run the query to create dot file (and bqrs as side effect)
    cd ~/w/codeql-javascript/
    codeql database analyze                                 \
           ~/w/codeql-javascript/src/callbacks.db/          \
           ~/w/codeql-javascript/queries/graphout.ql        \
           -j8 -v --ram=16000                               \
           --format=dot --rerun                             \
           --output=printast.dot

    # Create SVG version of graph
    cd ~/w/codeql-javascript/
    dot -Tsvg < ./printast.dot/null.dot > ./printast.dot/null.svg
    open -a safari printast.dot/null.svg

    # List query result meta info
    BQRS=src/callbacks.db/results/exploratory-queries-javascript/graphout.bqrs
    codeql bqrs info --format=text -- $BQRS

    # Format results using bqrs decode. 
    codeql bqrs decode --output=printast.csv --result-set=edges \
           --format=csv --entities=all -- $BQRS
    codeql bqrs decode --output=printast.json --format=json --entities=all -- $BQRS

    # Result files
    ls -1l ./src/callbacks.db/results/exploratory-queries-javascript/graphout.bqrs  \
       ./printast.dot/null.dot                                                      \
       printast.csv  printast.json
  #+END_SRC