Introduction

This is a tiny C++ parser created by using Flex and Bison for parsing the field specs like:

"U:3d:keep_vert_coord"
"calc_pt(P, T):3d"

in the father project geodiag-cmor. I store it here for demonstration the usage of Flex and Bison.

The test results are:

$ ./test
--> Input: 1
AST Nodes:
  [Number]: 1
--> Input: 2.0e+3
AST Nodes:
  [Number]: 2000
--> Input: U
AST Nodes:
  [ID]: U
--> Input: abs(U)
AST Nodes:
  [Function]: abs
  [ID List]:
  [ID]: U
--> Input: calc_pt(T, P, Q)
AST Nodes:
  [Function]: calc_pt
  [ID List]:
    [ID]: T
    [ID]: P
    [ID]: Q
--> Input: 1+2
AST Nodes:
  [Expression]:
    [Left]:
      [Number]: 1
    [Operator]: +
    [Right]:
      [Number]: 2
--> Input: 1.0e+3*(X+2)
AST Nodes:
[Expression]:
  [Left]:
    [Number]: 1000
  [Operator]: *
  [Right]:
    [Expression]:
      [Left]:
        [ID]: X
      [Operator]: +
      [Right]:
        [Number]: 2
--> Input: 2d:keep_vert_coord
AST Nodes:
  [Spec]: 2d
  [Spec]: keep_vert_coord
--> Input: U:[m s-1]
AST Nodes:
  [ID]: U
  [Spec]: units: m s-1

I referred http://panthema.net/2007/flex-bison-cpp-example/ and adapted the example there for my case. Thank Timo Bingmann for the great example!

Author

• Li Dong dongli@lasg.iap.ac.cn