Implement import and native commands

- `import`: imports the given `.h` file into the generated code;
- `native`:  directly calls a `C` language function.

Merge pull request #76 from haroldo-ok/native-command

This fixes #48

README.md

@@ -397,6 +397,36 @@ Sets the author of the story. Used to populate the ROM headers.
 * author "John Doe"
 ```
 
+### `import`
+Imports the given `.h` file into the generated code. Useful when combined with the `native` command.
+
+#### Positional parameters:
+* `fileName`: The name of the `.h` file.
+
+#### Example
+```shell
+* import "extra.h"
+```
+Will import "extra.h" into the generated `C` file.
+
+### `native`
+Directly calls a `C` language function.
+
+#### Positional parameters:
+* `functionName`: The name of the `C` function to call.
+
+#### Variadic parameters:
+All the positional parameters after `functionName` are passed as parameters to the function.
+
+#### Named parameters:
+* `into(variable)` if informed, will update the given variable with the return of the callsed function.
+
+#### Example
+```shell
+* native addExample, currentTick, 1 + 2, into(functionResult)
+```
+Will call the function `addExample` passing as parameters the value of the variable `currentTick` and the result of `1 + 2`; the result of the function will be stored in the `functionResult` variable.
+
 
 
 ## Planned commands

base/src/vn_engine.c

@@ -196,7 +196,7 @@ void VN_init() {
 	XGM_setLoopNumber(-1);
 	XGM_setForceDelayDMA(TRUE);
 
-	VDP_drawText("choice4genesis v0.9.1", 18, 27);
+	VDP_drawText("choice4genesis v0.10.0", 17, 27);
 }
 
 

examples/test/project/src/extra.c

@@ -0,0 +1,5 @@
+#include "extra.h"
+
+int addExample(int a, int b) {
+	return a + b;
+}

examples/test/project/src/extra.h

@@ -0,0 +1,6 @@
+#ifndef _EXTRA_H_
+#define _EXTRA_H_
+
+extern int addExample(int a, int b);
+
+#endif /* _EXTRA_H_ */

examples/test/project/startup.choice

@@ -90,5 +90,13 @@
 				Yet another line.
 				A really, really long line, to test a bit more.
 				Final line.
+			# Test native calls
+				* import "extra.h"
+				* temp currentTick, 0
+				* temp functionResult, 0
+				* native getTick, into(currentTick)
+				* native addExample, currentTick, 1 + 2, into(functionResult)
+				Current tick is ${currentTick}
+				Second function result is ${functionResult}
 			# Go to another scene
 				* goto_scene test

generator/generator.js

@@ -362,6 +362,33 @@ const COMMAND_GENERATORS = {
 		context.header.author = name;
 		return null;
 	},
+
+	'import': (entity, context) => {
+		const fileName = getStringConstant(entity, entity.params.positional.fileName, context, 'File name');
+		context.imports.push(fileName);
+		return null;
+	},
+
+	'native': (entity, context) => {
+		const functionName = getIdentifier(entity, entity.params.positional.functionName, context, 'Function name');
+
+		let assignment = '';
+		const named = entity.params.named || {};		
+		if (named.into) {
+			const varName = getIdentifier(entity, named.into.variable, context, 'Variable name');
+			const existingVar = context.locals.get(varName) || context.globals.get(varName);
+			if (existingVar) {
+				assignment = `${existingVar.value.internalVar} = `;
+			} else {
+				context.errors.push(buildEntityError(entity, `Couldn't find a variable named "${varName}".`));
+			}
+		}
+
+		const parameters = (entity.params.variadic || []).map((param, index) => 
+			getExpression(entity, param, context, `Parameter ${index + 1}`) || {});
+
+		return `${assignment}${functionName}(${parameters.map(expression => expression.code).join(', ')});`;
+	}
 };
 
 
@@ -463,7 +490,7 @@ const generateFromSource = (mainSourceName, context) => {
 	return {
 		sources: {
 			'generated_scripts.c': [
-				'#include "vn_engine.h"',
+				['vn_engine.h', ...context.imports].map(fileName => `#include "${fileName}"`).join('\n'),
 				generateVariableDeclarations(context.globals),
 				generatedForwards.join('\n'),
 				...generatedFunctions
@@ -487,6 +514,7 @@ const generate = fileSystem => {
 		choices: [],
 		globals: createNamespace(),
 		locals: null,
+		imports: [],
 		header: {
 			author: 'Unnamed Author',
 			title: 'Unnamed Story'

package.json

@@ -1,6 +1,6 @@
 {
   "name": "choice4genesis",
-  "version": "0.9.1",
+  "version": "0.10.0",
   "description": "A ChoiceScript clone that generates SGDK-compatible C source for the Sega Genesis ",
   "main": "index.js",
   "scripts": {

parser/expression.js

@@ -206,11 +206,18 @@ const buildResultObject = (result, lineNumber, config) => {
 	const errors = [];
 	const params = {};
 
-	const positional = collectPositionalArguments(result.value, config.positional, errors);	
-	validateTooManyArguments(result.value, config.positional, errors);
+	const positional = collectPositionalArguments(result.value, config.positional, errors);
+	const variadic = config.variadic ? (result.value || []).slice(positional.length).filter(param => param[0] !== 'NamedParam') : [];
+
+	if (!config.variadic) {
+		validateTooManyArguments(result.value, config.positional, errors);
+	}
 	if (positional.length) {
 		params.positional = Object.fromEntries(positional);
 	}
+	if (variadic.length) {
+		params.variadic = variadic;
+	}
 
 	const flags = collectFlags(result, config, errors);
 	if (flags.length) {

parser/syntax-full.js

@@ -40,7 +40,10 @@ const COMMANDS = {
 
 	'choice': { },
 	'scene_list': { },
-	'finish': { }	
+	'finish': { },
+
+	'import': { positional: ['fileName'] },
+	'native': { positional: ['functionName'], named: { into: ['variable'] }, variadic: true }
 };
 
 const COMMAND_PARSERS = Object.fromEntries(Object.entries(COMMANDS).map(([command, config]) => [command, createExpressionParser(config)]));