This is a list of reserved keywords you can use to create a syntax file for text editors:

catch
class
delay()
draw()
exit()
extends
false
final
implements
import
loop()
new
noLoop()
null
popStyle()
private
public
pushStyle()
redraw()
return
setup()
size()
static
super
this
true
try
void
cursor()
focused
frameCount
frameRate()
frameRate
height
noCursor()
online
screen
width
boolean
byte
char
color
double
float
int
long
Array
ArrayList
HashMap
Object
String
XMLElement
binary()
boolean()
byte()
char()
float()
hex()
int()
str()
unbinary()
unhex()
join()
match()
matchAll()
nf()
nfc()
nfp()
nfs()
split()
splitTokens()
trim()
Array Functions
append()
arrayCopy()
concat()
expand()
reverse()
shorten()
sort()
splice()
subset()
for
while
break
case
continue
default
else
if
switch()
PShape
arc()
ellipse()
line()
point()
quad()
rect()
triangle()
bezier()
bezierDetail()
bezierPoint()
bezierTangent()
curve()
curveDetail()
curvePoint()
curveTangent()
curveTightness()
box()
sphere()
sphereDetail()
ellipseMode()
noSmooth()
rectMode()
smooth()
strokeCap()
strokeJoin()
strokeWeight()
beginShape()
bezierVertex()
curveVertex()
endShape()
texture()
textureMode()
vertex()
loadShape()
shape()
shapeMode()
mouseButton
mouseClicked()
mouseDragged()
mouseMoved()
mousePressed()
mousePressed
mouseReleased()
mouseX
mouseY
pmouseX
pmouseY
key
keyCode
keyPressed()
keyPressed
keyReleased()
keyTyped()
BufferedReader
createInput()
createReader()
loadBytes()
loadStrings()
open()
selectFolder()
selectInput()
link()
param()
status()
day()
hour()
millis()
minute()
month()
second()
year()
print()
println()
save()
saveFrame()
PrintWriter
beginRaw()
beginRecord()
createOutput()
createWriter()
endRaw()
endRecord()
saveBytes()
saveStream()
saveStrings()
selectOutput()
applyMatrix()
popMatrix()
printMatrix()
pushMatrix()
resetMatrix()
rotate()
rotateX()
rotateY()
rotateZ()
scale()
shearX()
shearY()
translate()
ambientLight()
directionalLight()
lightFalloff()
lightSpecular()
lights()
noLights()
normal()
pointLight()
spotLight()
beginCamera()
camera()
endCamera()
frustum()
ortho()
perspective()
printCamera()
printProjection()
modelX()
modelY()
modelZ()
screenX()
screenY()
screenZ()
ambient()
emissive()
shininess()
specular()
background()
colorMode()
fill()
noFill()
noStroke()
stroke()
alpha()
blendColor()
blue()
brightness()
color()
green()
hue()
lerpColor()
red()
saturation()
PImage
createImage()
image()
imageMode()
loadImage()
noTint()
requestImage()
tint()
blend()
copy()
filter()
get()
loadPixels()
pixels[]
set()
updatePixels()
PGraphics
createGraphics()
hint()
PFont
Loading & Displaying
createFont()
loadFont()
text()
textFont()
textAlign()
textLeading()
textMode()
textSize()
textWidth()
textAscent()
textDescent()
PVector
abs()
ceil()
constrain()
dist()
exp()
floor()
lerp()
log()
mag()
map()
max()
min()
norm()
pow()
round()
sq()
sqrt()
acos()
asin()
atan()
atan2()
cos()
degrees()
radians()
sin()
tan()
noise()
noiseDetail()
noiseSeed()
random()
randomSeed()
HALF_PI
PI
QUARTER_PI
TWO_PI

This is another version of the keyword list you can use to make a syntax file for text editors, and it's probably more fit for the purpose than the previous one because functions are no followed by the round bracket pair ().

catch
class
delay
draw
exit
extends
false
final
implements
import
loop
new
noLoop
null
popStyle
private
public
pushStyle
redraw
return
setup
size
static
super
this
true
try
void
cursor
focused
frameCount
frameRate
frameRate
height
noCursor
online
screen
width
boolean
byte
char
color
double
float
int
long
Array
ArrayList
HashMap
Object
String
XMLElement
binary
boolean
byte
char
float
hex
int
str
unbinary
unhex
join
match
matchAll
nf
nfc
nfp
nfs
split
splitTokens
trim
Array Functions
append
arrayCopy
concat
expand
reverse
shorten
sort
splice
subset
for
while
break
case
continue
default
else
if
switch
PShape
arc
ellipse
line
point
quad
rect
triangle
bezier
bezierDetail
bezierPoint
bezierTangent
curve
curveDetail
curvePoint
curveTangent
curveTightness
box
sphere
sphereDetail
ellipseMode
noSmooth
rectMode
smooth
strokeCap
strokeJoin
strokeWeight
beginShape
bezierVertex
curveVertex
endShape
texture
textureMode
vertex
loadShape
shape
shapeMode
mouseButton
mouseClicked
mouseDragged
mouseMoved
mousePressed
mousePressed
mouseReleased
mouseX
mouseY
pmouseX
pmouseY
key
keyCode
keyPressed
keyPressed
keyReleased
keyTyped
BufferedReader
createInput
createReader
loadBytes
loadStrings
open
selectFolder
selectInput
link
param
status
day
hour
millis
minute
month
second
year
print
println
save
saveFrame
PrintWriter
beginRaw
beginRecord
createOutput
createWriter
endRaw
endRecord
saveBytes
saveStream
saveStrings
selectOutput
applyMatrix
popMatrix
printMatrix
pushMatrix
resetMatrix
rotate
rotateX
rotateY
rotateZ
scale
shearX
shearY
translate
ambientLight
directionalLight
lightFalloff
lightSpecular
lights
noLights
normal
pointLight
spotLight
beginCamera
camera
endCamera
frustum
ortho
perspective
printCamera
printProjection
modelX
modelY
modelZ
screenX
screenY
screenZ
ambient
emissive
shininess
specular
background
colorMode
fill
noFill
noStroke
stroke
alpha
blendColor
blue
brightness
color
green
hue
lerpColor
red
saturation
PImage
createImage
image
imageMode
loadImage
noTint
requestImage
tint
blend
copy
filter
get
loadPixels
pixels[]
set
updatePixels
PGraphics
createGraphics
hint
PFont
Loading & Displaying
createFont
loadFont
text
textFont
textAlign
textLeading
textMode
textSize
textWidth
textAscent
textDescent
PVector
abs
ceil
constrain
dist
exp
floor
lerp
log
mag
map
max
min
norm
pow
round
sq
sqrt
acos
asin
atan
atan2
cos
degrees
radians
sin
tan
noise
noiseDetail
noiseSeed
random
randomSeed
HALF_PI
PI
QUARTER_PI
TWO_PI