How to parse a string

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Let's say you want to add a node to the parse tree.

One simple way to do so is to start with a text string, then "parse" that string to get a VHDL or Verilog construct. The construct then can be added to the parse tree.

Below are the APIs to parse a string:

Verilog:

  • VeriExpression *veri_file::AnalyzeExpr(const char *expr, unsigned verilog_mode=VERILOG_2K, const linefile_type line_file = 0)
  • VeriModuleItem *veri_file::AnalyzeModuleItem(const char *module_item, unsigned verilog_mode=VERILOG_2K, const linefile_type line_file = 0, VeriScope *container_scope = 0)
  • VeriStatement *veri_file::AnalyzeStatement(const char *statement, unsigned verilog_mode=VERILOG_2K, const linefile_type line_file = 0, VeriScope *container_scope = 0)

Notes for Verilog :

- appropriate scope information where the given string is valid should be passed to the APIs for them to work properly
- need to call Resolve() on the returned parse tree nodes with proper scope where these items will be used
- VeriTreeNode::VERI_UPWARD_SCOPE_NAME can be passed as the Resolve() environment
- if required the nodes can be added to the existing parse tree using the appropriate APIs

VHDL:

  • VhdlExpression *vhdl_file::AnalyzeExpr(const char *expr, unsigned vhdl_mode=VHDL_93, const linefile_type line_file=0)
  • VhdlStatement *vhdl_file::AnalyzeSequentialStatement(const char *statement, unsigned vhdl_mode = VHDL_93, const char *lib_name = "work", const linefile_type line_file = 0, * VhdlScope *container_scope = 0)
  • VhdlStatement *vhdl_file::AnalyzeConcurrentStatement(const char *statement, unsigned vhdl_mode = VHDL_93, const char *lib_name = "work", const linefile_type line_file = 0, VhdlScope *container_scope = 0)
  • VhdlDesignUnit *vhdl_file::AnalyzeUnit(const char *unit, unsigned vhdl_mode = VHDL_93, const char *lib_name = "work", const linefile_type line_file = 0)

Notes for VHDL :

- appropriate scope information where the given string is valid should be passed to the APIs for them to work properly
- need vhdl_file::AnalyzeSequentialStatement() as well as vhdl_file::AnalyzeConcurrentStatement() to differentiate between the starting points of the two
- Verilog AnalyzeModuleItem() = both VHDL AnalyzeConcurrentStatement() and VHDL AnalyzeUnit()
- Verilog AnalyzeStatement() = VHDL AnalyzeSequentialStatement()

An example excerpt of C++ code using AnalyzeExpr() is as follows :

   VeriExpression *expr = veri_file::AnalyzeExpr(expr_string, veri_file::SYSTEM_VERILOG);
   VeriScope *current_scope = module->GetScope() ;
   if (expr) {
       myexp->Resolve(current_scope, VeriTreeNode::VERI_UPWARD_SCOPE_NAME);
       // plus anything else user may want to add
   }

Full designs can be analyzed from strings as well. Please use streams for that. See Analyzing Stream Inputs