Difference between revisions of "How to parse a string"

Revision as of 13:02, 17 June 2021

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 can then 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

Below is a C++ code example of using string parsing (veri_file::AnalyzeModuleItem()) to add a module to the parsetree.

#include <iostream>

#include "veri_file.h"
#include "VeriModule.h"
#include "VeriId.h"
#include "VeriScope.h"
#include "VeriLibrary.h"

#include "Array.h"

#ifdef VERIFIC_NAMESPACE
using namespace Verific ;
#endif

int main(void)
{
    // Analyze the file:
    Array files(1) ;
    files.InsertLast("test.sv") ;
    if (!veri_file::AnalyzeMultipleFiles(&files, veri_file::SYSTEM_VERILOG, "work")) return 1 ;

    // Get the 'top' module:
    VeriModule *top = veri_file::GetModule("top") ;
    if (!top) return 2 ;

    // Elaborate the 'top' module:
    if (!veri_file::ElaborateStatic(top->Name())) return 3 ;

    // Get the library of the 'top' module:
    VeriLibrary *work_lib = top->GetLibrary() ;
    if (!work_lib) return 4 ;

    // Get the compilation unit of the 'top' module and then the compilation unit scope where the class is declared:
    VeriModule *root = top->GetCompilationUnit() ;
    VeriScope *scope = (root) ? root->GetScope() : 0 ;

    // Analyze a new module under the scope of the compilation unit:
    VeriModuleItem *mi = veri_file::AnalyzeModuleItem("module test_A;\n    A tests[1];\nendmodule", veri_file::SYSTEM_VERILOG, 0UL, scope) ;
    if (!mi) return 5 ;

    // Get the identifier of the module item:
    VeriIdDef *id = mi->GetId() ;
    if (!id) return 6 ;

    // Get the VeriModule * from the identifier of the module:
    // This will return NULL if it is not actually a module.
    VeriModule *mod = id->GetModule() ;
    if (!mod) return 7 ;

    // Add the module to the same library as the 'top' module:
    if (!work_lib->AddModule(mod)) return 8 ;

    // Finally, elaborate the new module:
    if (!veri_file::ElaborateStatic(mod->Name())) return 9 ;

    veri_file::PrettyPrint("test_se.v.golden.new", 0) ;

    return 0 ;
}