From b87f8e3f4797203ad1541707ad6445aadae92145 Mon Sep 17 00:00:00 2001
From: Nicolas Hake <isilkor@openclonk.org>
Date: Tue, 11 Apr 2017 14:21:25 +0200
Subject: [PATCH] C4Script: Add ParseInt function

ParseInt() will take a string parameter and try to convert it into an
integer. If the conversion fails, it returns nil.
---
 docs/sdk/script/fn/ParseInt.xml         | 30 +++++++++++++++++++++++++
 src/lib/Standard.cpp                    |  9 +++++++-
 src/script/C4Script.cpp                 | 11 +++++++++
 tests/aul/AulPredefinedFunctionTest.cpp | 19 ++++++++++++++++
 4 files changed, 68 insertions(+), 1 deletion(-)
 create mode 100644 docs/sdk/script/fn/ParseInt.xml

diff --git a/docs/sdk/script/fn/ParseInt.xml b/docs/sdk/script/fn/ParseInt.xml
new file mode 100644
index 000000000..094ea17f2
--- /dev/null
+++ b/docs/sdk/script/fn/ParseInt.xml
@@ -0,0 +1,30 @@
+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<!DOCTYPE funcs
+  SYSTEM '../../../clonk.dtd'>
+<?xml-stylesheet type="text/xsl" href="../../../clonk.xsl"?>
+<funcs>
+  <func>
+    <title>ParseInt</title>
+    <category>Arithmetics</category>
+    <version>8.0 OC</version>
+    <syntax>
+      <rtype>int</rtype>
+      <params>
+        <param>
+          <type>string</type>
+          <name>value</name>
+          <desc>Absolute coordinate you want to convert to a relative coordinate.</desc>
+        </param>
+      </params>
+    </syntax>
+    <desc>Parses a string representing a base 10 number into an integer value. If the string does not entirely consist of a base 10 number, optionally signed, <code>nil</code> is returned.</desc>
+    <examples>
+      <example>
+        <code>ParseInt("14")</code>
+        <text>Returns the integer <code>14</code>.</text>
+        <code>ParseInt("fourteen")</code>
+        <text>Returns <code>nil</code>.</text>
+      </example>
+    </examples>
+  </func>
+</funcs>
diff --git a/src/lib/Standard.cpp b/src/lib/Standard.cpp
index 0acdaebcf..ac2357616 100644
--- a/src/lib/Standard.cpp
+++ b/src/lib/Standard.cpp
@@ -94,8 +94,9 @@ static int ToNumber(char c)
 
 //------------------------------- Strings ------------------------------------------------
 
-int32_t StrToI32(const char *s, int base, const char **scan_end)
+int32_t StrToI32(const char *str, int base, const char **scan_end)
 {
+	const char *s = str;
 	int sign = 1;
 	int32_t result = 0;
 	if (*s == '-')
@@ -107,6 +108,12 @@ int32_t StrToI32(const char *s, int base, const char **scan_end)
 	{
 		s++;
 	}
+	if (!*s)
+	{
+		// Abort if there are no digits to parse
+		if (scan_end) *scan_end = str;
+		return 0;
+	}
 	while (IsNumber(*s,base))
 	{
 		int value = ToNumber(*s++);
diff --git a/src/script/C4Script.cpp b/src/script/C4Script.cpp
index 042a9a4d0..26d3dddcd 100644
--- a/src/script/C4Script.cpp
+++ b/src/script/C4Script.cpp
@@ -617,6 +617,16 @@ static C4Value FnFormat(C4PropList * _this, C4Value * Pars)
 	return C4VString(FnStringFormat(_this, Pars[0].getStr(), &Pars[1], 9));
 }
 
+// Parse a string into an integer. Returns nil if the conversion fails.
+static Nillable<int32_t> FnParseInt(C4PropList *_this, C4String *str)
+{
+	const char *cstr = str->GetCStr();
+	const char *end = nullptr;
+	int32_t result = StrToI32(cstr, 10, &end);
+	if (end == cstr || *end != '\0') return C4Void();
+	return result;
+}
+
 static long FnAbs(C4PropList * _this, long iVal)
 {
 	return Abs(iVal);
@@ -1142,6 +1152,7 @@ void InitCoreFunctionMap(C4AulScriptEngine *pEngine)
 	for (C4ScriptFnDef *pDef = &C4ScriptFnMap[0]; pDef->Identifier; pDef++)
 		new C4AulDefFunc(p, pDef);
 #define F(f) ::AddFunc(p, #f, Fn##f)
+	F(ParseInt);
 	F(Abs);
 	F(Min);
 	F(Max);
diff --git a/tests/aul/AulPredefinedFunctionTest.cpp b/tests/aul/AulPredefinedFunctionTest.cpp
index e62d84497..190347cee 100644
--- a/tests/aul/AulPredefinedFunctionTest.cpp
+++ b/tests/aul/AulPredefinedFunctionTest.cpp
@@ -147,6 +147,25 @@ TEST_F(AulPredefFunctionTest, CreateEffect)
 	EXPECT_EQ(C4VInt(3), RunScript("local A = { Construction=func() { this.Magicnumber = 3; } }; func Main() { return CreateEffect(A, 1).Magicnumber; }"));
 }
 
+TEST_F(AulPredefFunctionTest, ParseInt)
+{
+	auto ParseInt = [this](const std::string &value) { return RunExpr("ParseInt(\"" + value + "\")"); };
+	EXPECT_EQ(C4VInt(0), ParseInt("0"));
+	EXPECT_EQ(C4VInt(0), ParseInt("-0"));
+	EXPECT_EQ(C4VInt(0), ParseInt("+0"));
+	EXPECT_EQ(C4VINT_MIN, ParseInt("-2147483648"));
+	EXPECT_EQ(C4VINT_MAX, ParseInt("2147483647"));
+
+	EXPECT_EQ(C4VNull, ParseInt(""));
+	EXPECT_EQ(C4VNull, ParseInt("-"));
+	EXPECT_EQ(C4VNull, ParseInt("+"));
+	EXPECT_EQ(C4VNull, ParseInt("--23"));
+	EXPECT_EQ(C4VNull, ParseInt("-+1234"));
+	EXPECT_EQ(C4VNull, ParseInt("a"));
+	EXPECT_EQ(C4VNull, ParseInt("0a"));
+	EXPECT_EQ(C4VNull, ParseInt("2147483647a"));
+}
+
 TEST_F(AulPredefFunctionTest, Trivial)
 {
 	EXPECT_EQ(C4VInt(100), RunExpr("Sin(900,100,10)"));