Add smart auto-completions

app/src/main/java/de/markusfisch/android/shadereditor/activity/MainActivity.java

@@ -19,6 +19,7 @@
 import android.os.Handler;
 import android.os.Looper;
 import android.util.DisplayMetrics;
+import android.util.Log;
 import android.view.KeyEvent;
 import android.view.LayoutInflater;
 import android.view.MotionEvent;
@@ -47,12 +48,15 @@
 import androidx.appcompat.widget.Toolbar;
 import androidx.core.content.ContextCompat;
 import androidx.core.view.ViewCompat;
+import androidx.recyclerview.widget.DiffUtil;
 import androidx.recyclerview.widget.DividerItemDecoration;
 import androidx.recyclerview.widget.LinearLayoutManager;
+import androidx.recyclerview.widget.ListAdapter;
 import androidx.recyclerview.widget.RecyclerView;
 
 import java.io.IOException;
 import java.io.InputStream;
+import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 import java.util.Objects;
@@ -73,7 +77,7 @@
 
 public class MainActivity
 		extends AppCompatActivity
-		implements ShaderEditor.OnTextChangedListener {
+		implements ShaderEditor.OnTextChangedListener, ShaderEditor.CodeCompletionListener {
 	private static final String SELECTED_SHADER = "selected_shader";
 	private static final String CODE_VISIBLE = "code_visible";
 	private static final int PREVIEW_SHADER = 1;
@@ -105,6 +109,8 @@ public void run() {
 	private volatile int fps;
 	private float[] qualityValues;
 	private float quality = 1f;
+	private final List<String> currentCompletions = new ArrayList<>();
+	private Adapter completionsAdapter;
 
 	@Override
 	public void onConfigurationChanged(@NonNull Configuration newConfig) {
@@ -139,6 +145,12 @@ public void onTextChanged(String text) {
 		setFragmentShader(text);
 	}
 
+	@Override
+	public void onCodeCompletions(@NonNull List<String> completions, int position) {
+		completionsAdapter.setPosition(position);
+		completionsAdapter.submitList(completions);
+	}
+
 	@Override
 	protected void onActivityResult(
 			int requestCode,
@@ -296,19 +308,8 @@ private void initExtraKeys() {
 		RecyclerView completions = extraKeys.findViewById(R.id.completions);
 		completions.setLayoutManager(new LinearLayoutManager(this, RecyclerView.HORIZONTAL,
 				false));
-		completions.setAdapter(new Adapter(this,
-				Arrays.asList(
-						"if",
-						"else",
-						"for",
-						"while",
-						"texture2D",
-						"distance",
-						"smoothstep",
-						"min",
-						"max"
-				)
-		));
+		this.completionsAdapter = new Adapter(this);
+		completions.setAdapter(completionsAdapter);
 		DividerItemDecoration divider = new DividerItemDecoration(completions.getContext(),
 				DividerItemDecoration.HORIZONTAL);
 		divider.setDrawable(Objects.requireNonNull(ContextCompat.getDrawable(this,
@@ -347,30 +348,47 @@ public void onGlobalLayout() {
 				: View.GONE);
 	}
 
-	private class Adapter extends RecyclerView.Adapter<Adapter.ViewHolder> {
-		private final List<String> list;
+	private static final DiffUtil.ItemCallback<String> DIFF_CALLBACK =
+			new DiffUtil.ItemCallback<String>() {
+				@Override
+				public boolean areItemsTheSame(@NonNull String oldItem, @NonNull String newItem) {
+					// Update the condition according to your unique identifier
+					return oldItem.equals(newItem);
+				}
+
+				@Override
+				public boolean areContentsTheSame(@NonNull String oldItem,
+						@NonNull String newItem) {
+					// Return true if the contents of the items have not changed
+					return oldItem.equals(newItem);
+				}
+			};
+
+	private class Adapter extends ListAdapter<String, Adapter.ViewHolder> {
+		@NonNull
 		private final LayoutInflater inflater;
+		int position = 0;
 
-		public Adapter(Context context, List<String> list) {
+		public Adapter(Context context) {
+			super(DIFF_CALLBACK);
 			this.inflater = LayoutInflater.from(context);
-			this.list = list;
 		}
 
 		@NonNull
 		@Override
-		public Adapter.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
+		public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
 			View view = inflater.inflate(R.layout.extra_key_btn, parent, false);
 			return new ViewHolder(view);
 		}
 
 		@Override
-		public void onBindViewHolder(@NonNull Adapter.ViewHolder holder, int position) {
-			holder.update(list.get(position));
+		public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
+			String item = getItem(position); // Use getItem provided by ListAdapter
+			holder.update(item);
 		}
 
-		@Override
-		public int getItemCount() {
-			return list.size();
+		public void setPosition(int position) {
+			this.position = position;
 		}
 
 		private class ViewHolder extends RecyclerView.ViewHolder {
@@ -379,7 +397,10 @@ private class ViewHolder extends RecyclerView.ViewHolder {
 			public ViewHolder(@NonNull View itemView) {
 				super(itemView);
 				btn = itemView.findViewById(R.id.btn);
-				btn.setOnClickListener((v) -> editorFragment.insert(btn.getText()));
+				btn.setOnClickListener((v) -> {
+					CharSequence text = btn.getText();
+					editorFragment.insert(text.subSequence(position, text.length()));
+				});
 				itemView.setOnTouchListener(new View.OnTouchListener() {
 					@SuppressLint("ClickableViewAccessibility")
 					@Override

app/src/main/java/de/markusfisch/android/shadereditor/fragment/EditorFragment.java

@@ -47,6 +47,8 @@ public View onCreateView(
 		if (activity instanceof ShaderEditor.OnTextChangedListener) {
 			shaderEditor.setOnTextChangedListener(
 					(ShaderEditor.OnTextChangedListener) activity);
+			shaderEditor.setOnCompletionsListener(
+					(ShaderEditor.CodeCompletionListener) activity);
 		} else {
 			throw new ClassCastException(activity +
 					" must implement " +

app/src/main/java/de/markusfisch/android/shadereditor/highlighter/Lexer.java

@@ -10,8 +10,9 @@
 import java.util.List;
 
 public class Lexer implements Iterable<Token> {
-	public String source(Token token) {
-		return source.substring(token.startOffset(), token.endOffset());
+	@NonNull
+	public static CharSequence tokenSource(@NonNull Token token, @NonNull CharSequence source) {
+		return source.subSequence(token.startOffset(), token.endOffset());
 	}
 
 	public static class Diff {
@@ -599,15 +600,50 @@ private int skipWhitespace() {
 		return possibleOctal && incorrectOctal ? TokenType.INVALID : type;
 	}
 
-	public static List<String> complete(@NonNull String text, @NonNull Token.Category type) {
+	public static List<String> completeKeyword(@NonNull String text, @NonNull Token.Category type) {
 		List<String> result = new ArrayList<>();
 		TrieNode root = tokenRoot(type);
 		if (root != null) {
 			root.findAll(text, (short) TokenType.INVALID.ordinal(), result);
 		}
+
+		if (type == Token.Category.PREPROC) {
+			// Also add normal keywords to the list
+			KEYWORDS_TRIE.findAll(text, (short) TokenType.INVALID.ordinal(), result);
+		}
+
 		return result;
 	}
 
+	/**
+	 * Performs a binary search to find the token that includes the given position.
+	 * Assumes tokens are non-overlapping and touch each other.
+	 *
+	 * @param tokens   List of tokens sorted by their start offsets.
+	 * @param position The offset to search for.
+	 * @return The token that contains the position, or null if no such token exists.
+	 */
+	@Nullable
+	public static Token findToken(@NonNull List<Token> tokens, int position) {
+		int low = 0;
+		int high = tokens.size() - 1;
+
+		while (low <= high) {
+			int mid = low + (high - low) / 2;
+			Token midToken = tokens.get(mid);
+
+			if (position >= midToken.startOffset() && position <= midToken.endOffset()) {
+				return midToken;
+			} else if (position < midToken.startOffset()) {
+				high = mid - 1;
+			} else {
+				low = mid + 1;
+			}
+		}
+
+		return null; // No token contains the position
+	}
+
 	@Nullable
 	private static TrieNode tokenRoot(@NonNull Token.Category type) {
 		switch (type) {