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using System;
using System.Dynamic;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;
namespace PGFSharp
{
/// <summary>
/// The class for PGF grammars.
/// </summary>
public class PGF
{
private PGF() { }
IntPtr _ptr;
NativeGU.NativeMemoryPool pool;
/// <summary>
/// Reads a grammar with the specified file path.
/// </summary>
/// <param name="fn">The path to the file.</param>
/// <returns>an object representing the grammar in memory.</returns>
public static PGF ReadPGF(string fn)
{
var obj = new PGF();
var exn = new NativeGU.NativeExceptionContext(new NativeGU.NativeMemoryPool());
obj.pool = new NativeGU.NativeMemoryPool();
obj._ptr = Native.pgf_read(fn, obj.pool.Ptr, exn.Ptr);
if (exn.IsRaised)
{
throw new PGFError($"Could not read PGF from file {fn}. ({System.IO.Directory.GetCurrentDirectory()})");
}
return obj;
}
public override string ToString() => $"Grammar:{Name}, {String.Join(", ", Languages.Keys)}";
/// <summary>
/// Name of the abstract grammar.
/// </summary>
public string Name => Native.NativeString.StringFromNativeUtf8(Native.pgf_abstract_name(_ptr));
/// <summary>
/// Default category of the grammar.
/// </summary>
public Type StartCat => Type.FromPtr(Native.pgf_start_cat(_ptr, pool.Ptr), pool);
/// <summary>
/// All concrete grammars in the language.
/// </summary>
public Dictionary<string, Concr> Languages
{
get
{
var dict = new Dictionary<string, Concr>();
Native.MapIter(Native.pgf_iter_languages, _ptr, (k, v) => dict[k] = Concr.FromPtr(this, dereference(v)));
return dict;
}
}
private IntPtr dereference(IntPtr ptr)
{
return (IntPtr)Marshal.PtrToStructure(ptr, typeof(IntPtr));
}
/// <summary>
/// All categories in the abstract grammar.
/// </summary>
public IEnumerable<string> Categories => GetStringList(Native.pgf_iter_categories);
/// <summary>
/// All functions in the abstract grammar.
/// </summary>
public IEnumerable<string> Functions => GetStringList(Native.pgf_iter_functions);
/// <summary>
/// Returns a list with all functions with a given return category.
/// </summary>
/// <param name="catName">The name of the return category.</param>
public IEnumerable<string> FunctionsByCat(string catName)
{
using (var str = new Native.NativeString(catName))
{
return GetStringList(new Native.IterFuncCurryName(Native.pgf_iter_functions_by_cat, str.Ptr).IterFunc);
}
}
/// <summary>
/// Returns the type of the function with the given name.
/// </summary>
/// <param name="funName">The name of the function.</param>
/// <returns></returns>
public Type FunctionType(string funName)
{
using (var str = new Native.NativeString(funName))
{
var typePtr = Native.pgf_function_type(_ptr, str.Ptr);
if (typePtr == IntPtr.Zero) throw new NullReferenceException();
return Type.FromPtr(typePtr, pool);
}
}
/// <summary>
/// Normalizes an expression to its normal form by using the 'def' rules in the grammar.
/// </summary>
/// <param name="expr">the original expression.</param>
/// <returns>the normalized expression.</returns>
public Expr Compute(Expr expr)
{
var tmp_pool = new NativeGU.NativeMemoryPool();
var exn = new NativeGU.NativeExceptionContext(tmp_pool);
var result_pool = new NativeGU.NativeMemoryPool();
var newExpr = Native.pgf_compute(_ptr, expr.Ptr, exn.Ptr, pool.Ptr, result_pool.Ptr);
if (exn.IsRaised || newExpr == IntPtr.Zero)
{
throw new PGFError("Could not reduce expression.");
}
else
{
return Expr.FromPtr(newExpr, result_pool);
}
}
/// <summary>
/// Returns an enumerable over the set of all expression in
/// the given category. The expressions are enumerated in decreasing
/// probability order.
/// </summary>
/// <param name="cat">the start category.</param>
/// <returns></returns>
public IEnumerable<Expr> GenerateAll(Type cat = null)
{
cat = cat ?? StartCat;
var tmp_pool = new NativeGU.NativeMemoryPool();
var exn = new NativeGU.NativeExceptionContext(tmp_pool);
var result_pool = new NativeGU.NativeMemoryPool();
IntPtr ptr = IntPtr.Zero;
var iterator = Native.pgf_generate_all(this._ptr, cat.Ptr, exn.Ptr, tmp_pool.Ptr, result_pool.Ptr);
return NativeGU.IteratorToIEnumerable(iterator, tmp_pool.Ptr).Select(p =>
{
var exprProb = Marshal.PtrToStructure<Native.PgfExprProb>(ptr);
return Expr.FromPtr(exprProb.expr, result_pool);
});
}
private IEnumerable<string> GetStringList(Native.MapIterFunc f)
{
var c = new List<string>();
Native.MapIter(f, _ptr, (k, v) => c.Add(k));
return c;
}
public dynamic Embed() {
return new GrammarEmbedding(this);
}
private class GrammarEmbedding : DynamicObject {
private PGF gr;
public GrammarEmbedding(PGF gr) {
this.gr = gr;
}
public override bool TryGetMember(GetMemberBinder binder, out object result)
{
result = null;
using (var str = new Native.NativeString(binder.Name))
{
var typePtr = Native.pgf_function_type(gr._ptr, str.Ptr);
if (typePtr == IntPtr.Zero)
return false;
}
result = new ApplicationExpr(binder.Name, new Expr[0]);
return true;
}
public override bool TryInvokeMember(InvokeMemberBinder binder, object[] args, out object result) {
result = null;
uint n_hypos = 0;
using (var str = new Native.NativeString(binder.Name))
{
var typePtr = Native.pgf_function_type(gr._ptr, str.Ptr);
if (typePtr == IntPtr.Zero)
return false;
n_hypos = NativeGU.SeqLength(Marshal.PtrToStructure<Type.PgfType>(typePtr).hypos);
}
if (args.Length != n_hypos)
return false;
Expr[] exprs = new Expr[args.Length];
for (var i = 0; i < args.Length; i++) {
exprs[i] = args[i] as Expr;
if (exprs[i] == null)
return false;
}
result = new ApplicationExpr(binder.Name, exprs);
return true;
}
}
}
}
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