Package org.spongepowered.asm.mixin.injection.points

Class BeforeStringInvoke

java.lang.Object

org.spongepowered.asm.mixin.injection.InjectionPoint

org.spongepowered.asm.mixin.injection.points.BeforeInvoke

org.spongepowered.asm.mixin.injection.points.BeforeStringInvoke

public class BeforeStringInvoke
extends BeforeInvoke

Like BeforeInvoke, this injection point searches for INVOKEVIRTUAL, INVOKESTATIC and INVOKESPECIAL opcodes matching its arguments and returns a list of insns immediately prior to matching instructions. This specialised version however only matches methods which accept a single string and return void, but allows the string itself to be matched as part of the search process. This is primarily used for matching particular invocations of Profiler::startSection with a specific argument. Note that because a string literal is required, this injection point can not be used to match invocations where the value being passed in is a variable.

To be precise, this injection point matches invocations of the specified method which are preceded by an LDC instruction. The LDC instruction's payload can be specified with the ldc named argument (see below)

The following parameters from At are accepted

target

A Target Selector which identifies the target method, the method must be specified with a signature which accepts a single string and returns void, eg. (Ljava/lang/String;)V

ordinal

The ordinal position of the method invocation to match. For example if the method is invoked 3 times and you want to match the 3rd then you can specify an ordinal of 2 (ordinals are zero-indexed). The default value is -1 which supresses ordinal matching

named argument: ldc

The value of the LDC node to look for prior to the method invocation

Example:

   @At(value = "INVOKE_STRING",
      target="startSection(Ljava/lang/String;)V", args = { "ldc=root" })

Notice the use of the named argument "ldc" which specifies the value of the target LDC node.

Note that like all standard injection points, this class matches the insn itself, putting the injection point immediately before the access in question. Use shift specifier to adjust the matched opcode as necessary.

Nested Class Summary

Nested classes/interfaces inherited from class org.spongepowered.asm.mixin.injection.points.BeforeInvoke

BeforeInvoke.SearchType

Nested classes/interfaces inherited from class org.spongepowered.asm.mixin.injection.InjectionPoint

InjectionPoint.AtCode, InjectionPoint.Flags, InjectionPoint.RestrictTargetLevel, InjectionPoint.Specifier

Field Summary

Fields inherited from class org.spongepowered.asm.mixin.injection.points.BeforeInvoke

allowPermissive, className, context, logger, mixin, ordinal, target

Fields inherited from class org.spongepowered.asm.mixin.injection.InjectionPoint

DEFAULT_ALLOWED_SHIFT_BY, MAX_ALLOWED_SHIFT_BY

Constructor Summary

Constructors

Constructor	Description
BeforeStringInvoke(InjectionPointData data)

Method Summary

Modifier and Type	Method	Description
boolean	find(String desc, org.objectweb.asm.tree.InsnList insns, Collection<org.objectweb.asm.tree.AbstractInsnNode> nodes)	Find injection points in the supplied insn list
protected void	inspectInsn(String desc, org.objectweb.asm.tree.InsnList insns, org.objectweb.asm.tree.AbstractInsnNode insn)
protected boolean	matchesOrdinal(int ordinal)

Methods inherited from class org.spongepowered.asm.mixin.injection.points.BeforeInvoke

addInsn, find, log, matchesInsn, setLogging

Methods inherited from class org.spongepowered.asm.mixin.injection.InjectionPoint

addMessage, after, and, before, checkPriority, getAtCode, getId, getSlice, getSpecifier, getTargetRestriction, nextNode, or, parse, parse, parse, parse, parse, parse, parse, parse, register, register, setTargetRestriction, shift, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Details

BeforeStringInvoke

public BeforeStringInvoke(InjectionPointData data)

Method Details

find

public boolean find(String desc,
 org.objectweb.asm.tree.InsnList insns,
 Collection<org.objectweb.asm.tree.AbstractInsnNode> nodes)

Description copied from class: InjectionPoint

Find injection points in the supplied insn list

Overrides:

find in class BeforeInvoke

Parameters:

desc - Method descriptor, supplied to allow return types and arguments etc. to be determined

insns - Insn list to search in, the strategy MUST ONLY add nodes from this list to the nodes collection

nodes - Collection of nodes to populate. Injectors should NOT make any assumptions about the state of this collection and should only call the add() method

Returns:

true if one or more injection points were found

inspectInsn

protected void inspectInsn(String desc,
 org.objectweb.asm.tree.InsnList insns,
 org.objectweb.asm.tree.AbstractInsnNode insn)

Overrides:

inspectInsn in class BeforeInvoke

matchesOrdinal

protected boolean matchesOrdinal(int ordinal)

Overrides:

matchesOrdinal in class BeforeInvoke